Example:multilpy 29 * 37
| Divide by 2 | Multiply by 2 | Add Only if |
|---|---|---|
| 29 | 37 | 37 |
| 14 | 74 | |
| 7 | 148 | +148 185 |
| 3 | 296 | +296 481 |
| 1 | 592 | +592 1073 |
The method is simple. Set up three columns.
Put the smaller number at the top of the first column.
Put the second number at the top of the second column.
If the number in the first column is odd, put the number from the second column into the third column.
Divide the number in the first column by two and write the new number below the top number. Disregard the remainder if any.
Add the number in the second column to itself. (Multiply by two) and write the new number below the perevious number.
If the new number in the first column is odd, put the new number from the second column into the third column, then add that number to any previous numbers.
Keep going until the number in the first column is 1.
Example:multilpy 16 * 17
| Divide by 2 | Multiply by 2 | Add Only if |
|---|---|---|
| 16 | 17 | |
| 8 | 34 | |
| 4 | 68 | |
| 2 | 136 | |
| 1 | 272 | +272 272 |
Example:multilpy 85 * 49
| Divide by 2 | Multiply by 2 | Add Only if |
|---|---|---|
| 85 | 49 | 49 |
| 42 | 98 | |
| 21 | 196 | +196 245 |
| 10 | 392 | |
| 5 | 784 | +784 1029 |
| 2 | 1568 | |
| 1 | 3136 | +3136 4165 |