Math and Logic

How Many Digits?

Our base-1010 system makes it easy to check whether a number is divisible by certain numbers. For example, checking whether 356356 is divisible by 22 or 55 comes down to checking whether the last digit is a multiple of either number. In this case, our number is divisible by 2,2, but not by 5.5.

Why does this work, though? Are there similar shortcuts for 44 and other numbers? Keep reading to find out, or skip ahead to the challenge for a puzzle on this idea.

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