Multiply a 3-digit number by a 1-digit number

Short multiplication

Partition the number into ones, tens and hundreds. Multiply these by the 1-digit number separately. Make sure everything is in the right place value column.

Example 1

What is 342 × 4?

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Start by multiplying the digit in the ones by 4. 2 × 4 = 8.
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Now multiply the tens by 4. 40 × 4 = 160. Place the 6 tens in the tens column and carry the hundred over into the hundreds column.
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Multiply 300 by 4. 300 × 4 = 1200. Don’t forget to add the hundred you carried over! 1200 + 100 = 1300. Place the 3 hundreds in the hundreds column and the 1 in the thousands column.
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Now you have solved it: 342 × 4 = 1368.

Example 2

What is 317 × 5?

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Multiply the ones by 5. 7 × 5 = 35. Keep the 5 in the ones column and carry over the 3 into the tens.
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Now multiply the tens by 5. 10 × 5 = 50. Add on the 3 extra tens that you carried over before. 50 + 30 = 80.
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Multiply 300 by 5. 300 × 5 = 1500.
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You have now solved it! 317 × 5 = 1585.