In the traditional method you write the bigger number above the smaller number, lining up digits with the same place values. Then subtract the digits in each column, starting from the right. Adjust 757 to 768 because 768 – 668 is easier to subtract. To do this you need to add 11. Now do the subtraction: 768 – 668 = 100 Amend this answer by subtracting 11. Answer: 100 – 11 = 89