Find the digit that makes 3, 71_ divisible by 9
A number is divisible by 9 if the sum of its digits is 9 or a multiple of 9
3+7+1=11
The next multiple of 9 nearer to 11 is 18
thus, 18-11=7
3+7+1=11
The next multiple of 9 nearer to 11 is 18
thus, 18-11=7