Use a number you know
To work out 12 × 4, split 12 into 10 + 2. Multiply both parts by 4, then add them.
The picture keeps all four rows. Only the columns are split.
Multiply both parts, then add
12 × 4
= (10 × 4) + (2 × 4)
= 40 + 8
= 48
The smaller part is also multiplied by 4. Adding only 2 would leave out three of the four rows.
Try one more column
Now try 13 × 4. Split 13 into 10 + 3, multiply each part by 4, and add.
Fractions, decimals and negatives
Work through the operations in order. Keep fractions exact and preserve negative signs.
(3/4 + 1/2) × 2 − 3 = 5/4 × 2 − 3 = 5/2 − 3 = −1/2
Work back to the missing number
Work backward from the final value: undo each step in reverse order to find the missing number, then substitute it to check.
(3/4 + □) × 2 − 1 = 3/2
3/2 + 1 = 5/2; 5/2 ÷ 2 = 5/4; 5/4 − 3/4 = 2/4 = 1/2
Try it
What is 13 × 4?
- 52
- 44
Show the answer
52
(10 × 4) + (3 × 4) = 40 + 12 = 52. You included all three extra columns in all four rows.
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