For any number 2^n(or 5^n), if you need to find out if it is a factor of number X, it is enough if you check the last n digits of the number X.
For ex., say a number 120016, if I need to find if the number is divisible by 16(=2^4), I just need to check if the last 4 digits is divisible by 4. So here 120016 is divisible by 16, because the last 4 digit is divisible by 16.
Now, let’s not convinced just with some shortcut.
Let’s understand the concept by taking a 5 digit number represented by abcde, where a,b,c,d,e each represents some decimal from 0 to 9.
I need to find out if the number abcde is divisible by 8(=2^3).
Expressing the number abcde as ab000 +cde
So now, ab000is nothing but abX1000, no doubt this is…
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