Multiply Numbers Near 100

Multiply two numbers just below 100 in seconds.

Cross-subtract the deficits, then multiply them.

1How it works

Write how far each number is below 100. The left part is one number minus the other’s deficit; the right part is the product of the two deficits, written as two digits.

2How to apply (in seconds)

Find each number’s deficit from 100 (96 → 4, 97 → 3).
Left part = first number − second deficit (96 − 3 = 93).
Right part = product of deficits (4 × 3 = 12), as two digits.

3Worked examples

Example 1 Worked solution

Q. Find 96 × 97.

Deficits: 4 and 3.
Left = 96 − 3 = 93.
Right = 4 × 3 = 12.

✓ 9312

4When to use it

✦Fast multiplication of numbers close to 100.

5Cautions & tips

!If the deficit product is a single digit, pad it to two digits (6 → 06).
!A similar method works near 50, 200 and 1000.