TI-BASIC, <s>20</s> 17
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Because it is tokenized, TI-BASIC is often competitive at simple math challenges, but not this one since there is no "divisible" command.

    not(fPart(Ans/400not(fPart(sub(Ansnot(fPart(Ans/4

This uses undocumented behavior of the `sub(` command, usually used to get a substring: when its argument is a number instead of a string, it divides the number by 100. This code will work on a TI-83 or 84 series calculator.

Edit: Saved three bytes by rearranging code to allow removal of close-parens.