# Summary

A teacher was told to prepare word problems for the students. She is given a list of equations and told to write them as the corresponding word problem. However, she is very lazy, so she doesn't put much creativity into it. Instead, she simply writes it literally. For example, when she reads 1+1, she writes one plus one, 47 * 2 would turn into forty seven times two, and 56.2 / 7.4 would become fifty six point two divided by seven point four.

Write some code to help this lazy teacher out.

## Details

• Numbers may include a decimal point and a negative sign.
• Numbers should be written in the short scale. (i.e., 1,000,000,000 is one billion)
• Numbers can go up to 999,999,999,999,999,999 (nine hundred ninety nine quadrillion...nine hundred ninety nine).
• Groups of zeros must be left out. e.g. 1,000,000 is one million not one million zero thousand zero hundred.
• There can be arbitrarily many digits past the decimal point.
• Digits after the decimal point must be listed digit by digit. e.g. 12.34 is twelve point three four not twelve point thirty four.
• Two numbers are always separated by an operator.
• The valid operators are plus (+), minus (-), times (*), and divided by (/).
• There are no parentheses.
• Numbers such as 1234 may optionally include an and in their output, as in one thousand two hundred *and* thirty four.
• Commas and whitespace on the input may be ignored.

## Examples

Input: 24 + 65
Output: twenty four plus sixty five

Input: 3.33333 - 0
Output: three point three three three three three minus zero

Input: 3.6 * 18.18 / 999.0
Output: three point six times eighteen point one eight divided by nine hundred ninety nine point zero

Input: 1-1
Output: one minus one

Input: 1+-1
Output: one plus negative one

Input: 1,000,000,000 + 0.2
Output: one billion plus zero point two

Input: 123,000,456,789,012,345.6789
Output: one hundred twenty three quadrillion four hundred fifty six billion seven hundred eighty nine million twelve thousand three hundred forty five point six seven eight nine

Input: -4.3 * 7
Output: negative four point three times seven

Input: -1-1--1
Output: negative one minus one minus negative one

• Could you add something like 123,456,789,012,345.6789 to the examples? It should cover a lot of test cases. – maxb Nov 27 '18 at 10:42
• Can we use minus instead of negative? – Jo King Nov 27 '18 at 10:55
• For Mathematica: again there is a builtin, but / is over and negative number is minus, so it needs some manipulation. – user202729 Nov 27 '18 at 11:21
• @user202729 Amazing... why am I not surprised Mathematica has a builtin for this? :) – Daffy Nov 27 '18 at 11:25
• Converting integers to English words – user202729 Nov 27 '18 at 11:27

# JavaScript (ES6), 552 532 bytes

This filthy monster comes straight from the depths of code-golfing hell.

Expects an input string without any whitespace.

S=>S[R='replace'](/[\d.,]+|./g,s=>1/s[0]?a(+s[S=0]&&14)+s[R](/(\D?)(\d+)/g,(_,s,n)=>s>','?' point'+n[R](/./g,a):j--*n?(u=a(n%10||14),n>99?a(n[0])+' hundred':'')+((n%=100)<13?a(n||14):n<20?(a(n)||u)+'teen':(a(n/10+18)||a(n/10))+'ty'+u)+a(j+27)+(j>1?'illion':''):'',j=s.split,.length):a(S='+-*/'.indexOf(s=='-'&&S||s)+34),a=n=>(s='zero0one0two0three0four0five0six0seven0eight0nine0ten0eleven0twelve0thir00fif000eigh00twen0thir0for0fif000eigh00thousand0m0b0tr0quadr0negative0plus0minus0times0divided by'.split0[n|0])&&' '+s).trim()


Try it online!

• You can cut 18 bytes by replacing your giant string literal with btoaÍêèÒ‰ÞÒÜ(ÒØkyí¢êô~+ÞÒÈ±ÒÇ¯z}ŠmÒx§{K^ŸG¥z÷§ÒÜ–÷´¶«ÓGâM4z(!ÓKpz}-†*ô~Šô~'ôÓG¢‚4¶.±©ÝÒmÒÚôªæ�¯IÞ�«b½í)–ë4š)î³Kb™ë4v+âuçu×Vò.replace(111,' '). – kamoroso94 Nov 27 '18 at 19:09
• I love responses that creatively compress string literals like this. – Daffy Nov 27 '18 at 21:31

# Perl 6, 434 401 387 359 bytes

{~S:g/\d+/{n($//100+64184)x($/>100),$/%100>19&&(n($//10%10+64175),n($!=$/%10)x?$!)||n($/%100+7679),[$,"thousand",|(<m b tr quadr>X~"illion")][+$/.postmatch.words[0].comb(',')]if +$/} /.trans("+,-/*"=><<plus''minus"divided by"times>>).words}o{S:g/\.(\d)+/ point {$0>>.&n}/}o{S:g/[\s|^]0/ zero/}o{S:g/\-(\d)/negative $0/} my&n=(*+1632+|0).uniname.lc.words[2..*]  Try it online! Definitely room for improvement here. I say that, but I keep noticing edge cases I haven't handled :(. Assumes that the input has operators separated by whitespace and the negative of a number isn't separated. ### Explanation: my&n=(*+1632+|0).uniname.lc.words[2..*] # Define a helper function # This gets the unicode name, e.g ARABIC-INDIC DIGIT ZERO # or AEGEAN NUMBER ONE HUNDRED # And returns the 3rd word onwards in lowercase e.g. 'zero' or 'one hundred' {S:g/\-(\d)/negative$0/}  # Turn dashes before numbers to negative
{S:g/[\s|^]0/ zero/}       # Handle zeros
{S:g/\.(\d)+/ point {$0>>.&n}/} # Replace decimals {~S:g/\d+/ # Replace series of numbers with n($//100+64184)x($/>100) # The hundreds if the num is bigger than 100$/%100>19&&               # If the number is bigger than 19
(
n($//10%10+64175), # The tens number n($!=$/%10)x?$!            # And the singles number (if it's not zero)
)
||                        # Else
n($/%100+7679) # The name of the number below 20 , # Then [$,"thousand",|(<m b tr quadr>X~"illion")][   # Index into the list of postfixes
+                         .comb(',')   # The number of commas
$/.postmatch.words[0] # in the rest of the number if +$/           # All if the number is not 0
.trans("+,-/*"=><<plus''minus"divided by"times>>)  # Translate operators
# And remove commas
.words}     # And remove all the excess spaces between words


# Ruby + Swift 4, 283279 270 bytes

$_=gsub(/(?<=\d)-/,"minus ").gsub(/[*-\/]/,?.=>"point ",?-=>"negative ",?+=>"plus ",?*=>"times ",?/=>"divided by ").gsub(/(?<=^|[^t] )\d+|\d/){echo "import Foundation var f=NumberFormatter() f.numberStyle = .spellOut print(f.string(from:#$&)!)">.a
swift .a.tr'-
',' '}


Try it online!

I must be mad to propose such a Frankenstein solution, but on one hand, it is very tempting to use Swift's built-in functionality for this task, and on the other hand, processing strings with Regexes in Swift looks to be a golfing catastrophe.

Therefore, I decided to do basic string processing in Ruby, but to spell out numbers, I store them in a Swift source file, run Swift in a shell command, and collect the output.

I turns out that Swift's "spellOut" number formatter does almost exactly what we need, except inserting unnecessary hyphens for two-digit numbers, as in twenty-two. In fact, even the floating point output in the format of integer part point digit digit... is good, but here comes the caveat - there is no infinite precision, and with large enough numbers or a lot of decimal digits, the results go wrong. Therefore, I had to separate the integer and fractional parts and to feed the fraction digit by digit.

• This is absolutely diabolical and I love it. – Daffy Nov 28 '18 at 22:02

# sfk, 853 bytes

xed -i
"_*_ [part1]_"
+xed
_+_plus_
_\*_times_
"_/_divided by_"
"_- _minus _"
"_-_negative _"
+xed
"_,[keep][19 chars of 0-9,]_quadr@ _"
"_,[keep][15 chars of 0-9,]_tr@ _"
"_,[keep][11 chars of 0-9,]_b@ _"
"_,[keep][digits],[digits],_b@ _"
"_,[keep][digits],_m@ _"
"_,_ thousand _"
+xed
"_ 000[chars]@__"
"_ 000__"
"_ 00[keep][digit]_ _"
"_ 0[keep][2 digits]_ @_"
"_ [digit][keep][2 digits]_[part2]hundred @_"
"_ [ortext] 0[digit]0_ @[part2]_"
"_ [keep][2 digits]_ @_"
"_@_illion _"
+xed
_@11_eleven_
_@12_twelve_
_@1[digit]_@[part2]teen_
_@1_ten_
_@4_forty_
_@[digit]_@[part2]ty_
+xed
_@2_twen_
_@3_thir_
_@4_four_
_@5_fif_
_@6_six_
_@7_seven_
_@8_eigh_
_@9_nine_
+xed
"_0_ zero _"
"_1_ one _"
"_2_ two _"
"_3_ three _"
"_4_ four _"
"_5_ five _"
"_6_ six _"
"_7_ seven _"
"_8_ eight _"
"_9_ nine _"
"_._ point _"
+xed
"_[white]_ _"
+xed
"_[lstart] __"



Try it online!

Requires operators and numbers be separated by at least one space character.

# Clean, 766 ... 687 bytes

import StdEnv,Text
m=""
z="zero"
@ =digitToInt
r=reverse
l k=(!!)k o@
^s=l[s:split" ""one two three four five six seven eight nine"]
g s=l[m,m,"twen","thir",s,"fif","six","seven","eigh","nine"]
~['0':t]= ~t
~[a,b,c]= ^""a+" hundred "+ ~[b,c]
~[b,c]|b>'1'=g"for"b+"ty "+ ^""c|c>'2'=g"four"c+"teen"=["ten","eleven","twelve"]!!(@c)
~[c]= ^""c
~_=m
$[]=m$[x:y]#(h,t)=span(\e=e>'/'||e==',')if(x<'1')y[x:y]
=trim(join" "((case x of'0'=[z];'-'=["negative",$h];'.'=["point":map(^z)h];_=(r[u+v\\u<-r(map~(split[',']h))&v<-[m," thousand":[" "+k+"illion"\\k<-["m","b","tr","quadr"]]]|u>m]))++[?t])) ?['-':t]="minus "+$t
?['+':t]="plus "+ $t ?['/':t]="divided by "+$t
?['*':t]="times "+ $t ?t=$t


Try it online!

Expects a string without whitespace.

# 05AB1E, 315295282 276 bytes

"+-*/"DˆS¡εDõQi'¢…ë'.¡VYнD_i\'¡×ðë',¡DgUε0›i.•6b©•ð“†ìˆÈŒšï¿Ÿ¯¥Š“©'tKJ#'…§«…€µ‚•„í#®#«…—¿áÓÁÏ#«ìD9£©.•4º»Ÿć'Rþн•ŽH$S£“Œšï¿Ÿ¯¥Š“'tK#«„ty«sõšâðý«õšD®'°¡ðì«sâðý«yèð.•cG3₅¦„¥F•8ô'¾ß«…¡›‡È±°#«õªRXN-<èJëõ}}ðý}Yg<i®'¡×šYθSè'…®šðý}}J}s¯Ãε“‰´Øè„Æºß“#¤… by«¸s¨ì¯ykè}.ιðý„ ð:„¢…Øè'¢…:  Takes input without any spaces. Explanation: "+-*/" # Push string "+-*/" Dˆ # Duplicate it, pop the copy, and push it to the global array S¡ # Split the input by any "+", "-", "*", or "/" ε # Map each number to: DõQi # If the item is empty (happens for negative numbers) '¢… '# Push string "negative" ë # Else: '.¡ '# Split by "." VY # Store it in variable Y н # Take the first number (the integer part) D # Duplicate this integer part _i # If the integer part is exactly 0: \ # Discard the duplicated integer part '¡× '# Push string "zero" ð # Push a space " " ë # Else: ',¡ '# Split by "," DgU # Pop and store the amount of items in variable X ε # Map each part to: 0›i # If it's larger than 0: .•6b©• # Push string "thir" ð # Push a space " " “†ìˆÈŒšï¿Ÿ¯¥Š“ # Push string "four five six seven eight nine" © # Store it in the register (without popping) 'tK '# Remove all "t" (so "eight" becomes "eigh") J # Join it together with the "thir" and space # # Split by spaces '…§ '# Push string "teen" « # And append it to every string in the list # (We now have ["thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"]) …€µ‚•„í # Push string "one two three" # # Split by spaces ® # Push the string from the register ("four" through "nine") #« # Split by spaces, and merge both lists together …—¿áÓÁÏ # Push string "ten eleven twelve" #« # Split by spaces, and also merge both lists together ì # Prepend "one" through "twelve" before "thirteen" through "nineteen" D9£ # Duplicate it, and take the first nine ("one" through "nine") © # Store it in the register (without popping) .•4º»Ÿć'Rþн• '# Push string "twenthirforfif" ŽH$             #      Push integer 4433
S            #      Split to digits: [4,4,3,3]
£           #      And split the to parts of that size: ["twen","thir","for","fif"]
“Œšï¿Ÿ¯¥Š“      #      Push string "six seven eight nine"
'tK  '#      Remove all "t" (so "eight" becomes "eigh")
#« #      Split by spaces, and merge both lists together
„ty             #      Push string "ty"
«            #      And append it to every string in the list
#      (We now have ["twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"])
s               #      Swap so the list "one" through "nine" is at the top again
õš             #      Prepend an empty string to that list
â            #      Create every possible pair of "one" through "nine" with "twenty" through "ninety"
ðý          #      Join each pair with a space delimiter
«               #      Merge the "twenty" through "ninety nine" list with "one" through "nineteen"
õš             #      Prepend an empty string to that list
D               #      Duplicate the entire list
®               #      Push the string from the register ("one" through "nine")
'°¡            '#      Push string "hundred"
ðì           #      Prepend it with a space " "
«          #      Append it to every string in the list
#      (We now have ["one hundred","two hundred",...,"nine hundred"])
s               #      Swap the two lists
â              #      Create every possible pair of "one hundred" through "nine hundred" with "" through "ninety nine"
ðý            #      Join each pair with a space delimiter
«           #      Merge the "one" through "ninety nine" with "one hundred " through "nine hundred ninety nine"
#      (We now have ["","one",...,"nine hundred ninety nine"])
y               #      Get the current number of the map
è              #      And index it into this list
ð               #      Push a space " "
.•cG3₅¦„¥F•     #      Push string "quadrilltrill"
8ô   #      Split into pieces of size 8: ["quadrill","trill"]
'¾ß            '#      Push string "ion"
«            #      Append it to every string in the list
…¡›‡È±°         #      Push string "billion million thousand"
#        #      Split by spaces
«       #      And merge both lists together
õª              #      Append an empty string
R             #      Reverse the list
#      (We now have ["","thousand","million","billion","trillion","quadrillion"])
X               #      Push variable X
N-             #      Subtract the map-index from it
<            #      Subtract an additional 1
è           #      And index it into the list
J               #      Join the stack together
ë                  #     Else:
õ                 #      Push an empty string ""
}                  #     Close the if-else
}                   #    Close the map
ðý                  #    Join the mapped values with space delimiter
}                       #   Close the if-else
Y                       #   Push variable Y
g<i                     #   If its length is exactly 2:
®                    #    Push the string from the register ("one" through "nine")
'¡×                 '#    Push "zero"
š                 #    Prepend it to the list
Yθ                  #    Push variable Y again, and leave the second number (the decimal part)
S                 #    Split it to digits
è                #    And index each into the list
'…®                '#    Push string "point"
š                #    Prepend it in front of that list
ðý                  #    Join the list with space delimiter
}                       #   Close the if
}                        #  Close the if-else
J                        #  Join the stack together
}                         # Close the map
s                         # Swap to take the (implicit) input again
¯                        # Push the global array, and dump it's content (string "+-*/")
Ã                       # Only keep all "+", "-", "*", and "/", and remove everything else
ε                         # Map each to:
“‰´Øè„Æºß“               #  Push string "plus minus times divided"
#              #  Split by spaces
¤                        #  Take the last item (without popping the list)
… by«                   #  Append it with string " by"
¸                  #  Wrap it to a list: ["divided by"]
s                        #  Swap to take the list again
¨                       #  Remove the last item
ì                      #  Prepend it in front of the list: ["plus","minus","times","divided by"]
¯                       # Push the global array, and dump it's content (string "+-*/")
yk                     #  Push the index in this string for the current map-value y
è                    #  And use that index to index into the string-list
}                         # Close the map
.ι                        # Interweave the list of numbers and list of operators
ðý                      # Join everything with space delimiter
„  ð:                     # Replace every two spaces for a single space
„¢…Øè'¢…:                '# And replace every "negative minus" with "negative"
# (and output the result implicitly)

• (How to use the dictionary?) -- '¢… is "negative"; '¡× is "zero"; “†ìˆÈŒšï¿Ÿ¯¥Š“ is "four five six seven eight nine"; '…§ is "teen"; …€µ‚•„í is "one two three"; …—¿áÓÁÏ is "ten eleven twelve"; '°¡ is "hundred"; '¾ß is "ion"; …¡›‡È±° is "billion million thousand"; '…® is "point"; and “‰´Øè„Æºß“ is "plus minus times divided".
• (How to compress strings not part of the dictionary?) -- .•6b©• is "thir"; .•4º»Ÿć'Rþн• is "twenthirforfif"; and .•cG3₅¦„¥F• is "quadrilltrill".
• (How to compress large integers?) -- ŽH\$ is 4433.

# Python 2, 790 774 bytes

lambda T:B("([+/*-])",lambda m:dict(zip("+/*-",S("z"," plus z divided by z times z minus ")))[m.group(0)],B("([+/*-]|^)-",r"\1negative ",B("[^+/*-]+","{}",T))).format(*[J([g[int(S("\.",j)[0])]+S("z",B("y","illion","z thousandz myz byz tryz quadry"))[len(S(",",m))+~i]+(" point "+J(s[int(c)]for c in S("\.",j)[-1]))*("."in j)for i,j in E(S(",",m))if 0<float(j)+(m<"1")])for m in S("[+/*-]+",T)[T[0]=='-':]])
from re import*
E,S,B,P=enumerate,split,sub," ";J=P.join
s,e=S(P,"zero one two three four five six seven eight nine"),[B("urty","rty",j)for i,j in E(c+d for d in S(P,"teen ty")for c in S(P,"twen thir four fif six seven eigh nine"))]
g=s+S(P,"ten eleven twelve")+e[1:8]+[a+(P+b)*(i>0)for a in e[8:]for i,b in E(s)]
g=[(j+" hundred ")*(i>0)+k for i,j in E(s)for k in g]


Try it online!

So many bad practices. This almost hurt to write....

Expects a non-unicode string with no whitespace as input.

Explanation:

# import all functions from re (python regex library)
from re import*

# rename some repeatedly-used functions/variables for reduced bytecount
E,S,B,P=enumerate,split,sub," ";J=P.join

# list the names of 0-9
s=S(P,"zero one two three four five six seven eight nine")
# generate "twenteen" through nineteen and twenty though ninety, changing "fourty" to forty
# using enumerate (E) even though i is not required b/c it's shorter than range(len(x))
# using re.split (S) instead of string.split since it's shorter
e=[B("urty","rty",j)for i,j in E(c+d for d in S(P,"teen ty")for c in S(P,"twen thir four fif six seven eigh nine"))]
# generate 0-999
# 0-9
g=s+
# 10, 11, 12
+S(P,"ten eleven twelve")+
# remove "twenteen", 13-19
+e[1:8]+
# tens' place + ones' place, if ones' place is not zero
+[a+(P+b)*(i>0)                               ]
# for each tens' place in 20-90
for a in e[8:]
# for each index, value in ones' places 0-9
for i,b in E(s)

# hundreds' place if at least 100, plus tens' and ones' place (already calculated and stored in g from before)
g=[(j+" hundred ")*(i>0)+k                          ]
# (s) stores names for 0-9, need index to avoid "zero hundred"
for i,j in E(s)
# for each hundred, iterate over all values (0-99) already in g
for k in g

# actual function to call. uses previously declared global variable g.
def f(T):
# gets the numbers in the supplied string (T) by splitting (T) on any operator character
# remove first item if blank (only happens when staring with a - for negative numbers)
n=S("[+/*-]+",T)[T[0]=='-':]

# triply-nested set of re.subs to convert (T) to a sting of where the operators are replaced by their names and numbers are replaced by "{}"
# EX: "-1-1--1" -> "-{}-{}--{}" -> "negative {}-{}-negative {}" -> "negative {} minus {} minus negative {}"
# this sub happens last
# re.sub (B) any operator, with the operators in a group "()" so that they return in match.group
T=B("([+/*-])",                                                                                                                                        )
# an anonymous function to accept match objects (m) from re.sub's search.
,lambda m:
# create a dictionary from the combination of operators and their names
# like {"+":" plus ",...}
# operator names are surrounded by spaces since number names are NOT
dict(zip("+/*-",S("z"," plus z divided by z times z minus ")))
# from the constructed dictionary, select the operator matched by re.sub's search and return it for replacement
[m.group(0)],
# this substitution is second
# re.sub (B) any operator followed by a minus (-), OR a minus at the beginning of the string
# operators/start are grouped, trailing minus is not
,B("([+/*-]|^)-",                                    )
# replace match with the grouped items plus the word "negative"
# EX: "-1-1--1" -> "-{}-{}--{}" -> "negative {}-{}-negative {}"
,r"\1negative ",
# this substitution is done first
# replace any sequence of NON-operators with "{}"
# this removes numbers so the names can be inserted later
# EX: "-1-1--1" -> "-{}-{}--{}"
,B("[^+/*-]+","{}",T))

# technically the previous construction of (T) and (n) can be placed here to save 5 bytes but my poor eyes can't handle that.
# insert constructed names back into original string.
# EX: "-1-1--1" -> "negative {} minus {} minus negative {}" -> "negative one minus one minus negative one"
print T.format(                                                                                                                                                                                                                     )
# string.format needs items in array unpacked, or it will attempt to insert the string representation of the array itself
*[                                                                                                                                                                                                                  ]
# for each number pulled from (T), generate names and join generated items back together with spaces
# EX: "1,456" -> ["1", "456"] -> ["one thousand", "four hundred fifty six"] -> "one thousand four hundred fifty six"
J(                                                                                                                                                                                                     )for m in n
# split j on periods (.) and take the first item
# convert that item into an integer and find the item at that index in g (0-999)
[g[int(S("\.",j)[0])]+                                                                                                                                                                              ]
# insert prefix for millions +, split string on "z" (spaces must be preserved for proper separation)
+S("z",B("y","illion","z thousandz myz byz tryz quadry"))
# left is largest, so take the item at index (total # of groups - current place - 1)
[len(S(",",m))+~i]+
# if group had a period, split string on period and take last item
# replace every character in group with number 0-9 name
# join them with spaces and add back to rest of group
+(" point "+J(s[int(c)]for c in S("\.",j)[-1]))*("."in j)
# split number into groups by comma
# EX: "123,456" -> ["123","456"]
# only return item if j != 0 (avoids returning empty string which will result in too many joined spaces)
# OR if m == 0 (avoids not returning anything when should return "zero")
for i,j in E(S(",",m))if 0


I reduced by about 150 bytes while writing the explanation. Let it never be said that commenting/reviewing your code isn't helpful!