Multiplying bigger numbers by splitting
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What you will learn
By the end, you can multiply numbers like 36 × 5 or 124 × 3 by splitting them into parts you know.
Fatou runs a fruit stall. A customer wants 23 boxes of mangoes, 4 in each box. Fatou does not know 23 × 4 by heart, but she knows 20 × 4 and 3 × 4. Two easy sums, one quick answer: 92.
Read the explanation
Big numbers are easier in pieces. Split (partition) the big number into hundreds, tens and ones, multiply each piece by the small number, then add the pieces back together. A grid keeps the pieces tidy.
- Split: 124 = 100 + 20 + 4.
- Multiply each part: 100 × 3, 20 × 3 and 4 × 3.
- Add the parts: 300 + 60 + 12 = 372.