# [JavaScript (Babel Node)], 43 bytes

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    f=(a,b)=>a+b&&a%10+b%10+19*f(a/10|0,b/10|0)

[Try it online!][TIO-k9uikbu2]

[JavaScript (Babel Node)]: https://babeljs.io/
[TIO-k9uikbu2]: https://tio.run/##HYhBDoIwEADvvoIDklYW3AUb9AAfaRrYKhgNUiLGC/J2tF5mMnPnN0/n5218JZZt2yeDu7Tr2pWCwcqy4thGEW8JY@tBp10neE/4QbB/yfXshsn1bdq7q9CaIDOgFRD@dMgg90mqoAIU5eroCxGBjEkfPIq6rBodzrVGs4A3mcUESRWEcyf8Bb/k0ki5Wb8 "JavaScript (Babel Node) – Try It Online"