Question

Can you explain the divisibility rule of 7?

Answer 1

To find out if a number is divisible by 7, take the last digit, double it, and subtract it from the rest of the number.
If you get an answer divisible by 7 (including zero), then the original number is divisible by seven. If you don’t know the new number’s divisibility, you can apply the rule again.
: Check to see if 203 is divisible by 7.
Example
· double the last digit: 3 $\times$ 2 = 6
· subtract that from the rest of the number: 20 - 6 = 14.
· check to see if the difference is divisible by 7: 14 is divisible by 7, therefore 203 is also divisible by 7.