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Here is an example of multiplication of decimal numerals using the schoolbook method, which is also called “Long Multiplication”:
| 7 | 4 | 3 | 8 | (upper operand) | |||
| 9 | 3 | 6 | (lower operand) | ||||
| 4 | 4 | 6 | 2 | 8 | |||
| 2 | 2 | 3 | 1 | 4 | |||
| 6 | 6 | 9 | 4 | 2 | |||
| 6 | 9 | 6 | 1 | 9 | 6 | 8 |
We iteratively pick each digit bi of the lower operand b, starting at the LSD (position 0), and multiply it with the complete upper operand a to produce one “row” Ri. Each such row Ri is left-shifted by i positions. The result of (a ⋅ b) is addition of these left-shifted rows.
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