Read first
Try this before the method.
98 × 97. Ten seconds.
Try it in your head before you continue.
Ordinary multiplication works. But can you see a quicker route because both numbers are close to 100?
Now reveal the shortcut
Each number is only a small distance below 100: 98 is 2 below, and 97 is 3 below. Those distances are called deficits.
Cross-subtract one deficit from the other factor to make the left block: 98 − 3 = 95. Multiply the two deficits for the right block: 2 × 3 = 6.
With Base 100, the right block always keeps two places. Write 6 as 06, then join the blocks: 95 | 06 = 9506.
Numbers above 100 use the same rhythm. Their distances are surpluses, and cross-subtraction becomes cross-addition. In both cases, the two blocks keep the structure of the answer visible while you work.