For this case we have the following operation:
538 - 247
To subtract both numbers we must follow the following steps:
1) Subtraction is done from left to right:
2) We subtract the first digits:
8 - 7 = 1
3) We subtract the second digits:
3 - 4
Since 4 is greater than 3 then we add a digit to 3 and accumulate it for the next subtraction:
13 - 4 = 9
4) We subtract the digit accumulated in the previous subtraction to the following number:
5 - 2 - 1 = 2
Finally the result is:
538 - 247 = 291