Comments by "Abigor Anathema" (@kruksog) on "15 невероятных математических фактов | Безумно, но верно" video.

  1. The fact that any number which is divisible by 9 has a digit-sum of 9 is pretty easy to see if you consider two facts: we use base-10 (i.e. the number 'abc' = a×10^2+b×10^1+c×10^0) and 10 has remainder 1 when divided by 9.
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