Subtracting Two Digit Numbers without Renaming
How to subtract twodigit numbers (for example 67  45).
 Place one number above the other so the tens' place digits and ones' place digits
are lined up. Draw a line under the bottom number.
67
45
 Subtract the bottom ones' place digit (5) from the top ones' place digit (7) and
place the difference (2) below the line in the ones' place column.
67
45
2
 Subtract the bottom tens' place digit (4) from the top tens' place digit (6).
Place the difference (2) below the line in the tens' place column.
67
45
22
