Multiplying 2 and 3-digit numbers by a 1-digit number
In a nutshell
It is common to use written methods when multiplying three-digit numbers and trickier two-digit numbers by a one-digit number, however, mental methods are still very useful.
Written methods
Short multiplication is a common written method for multiplying two- and three-digit numbers by a one-digit number.
Short multiplication
Using columns to set out and calculate, short multiplication is a quick way to work out multiplication calculations.
PROCEDURE
1. | Set out the calculation: - Align the ones one below the other ones and write out the rest of the digits in columns.
- Draw a line beneath and a multiplication symbol to the left.
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2. | Multiply each digit of the two/three-digit number by the single digit from right to left. |
3. | Below the line in the answer space, write the unit digit of each calculation and carry over into the next column if required. |
Example
Work out 132×4.
Set out the calculation.
Multiply each digit of the two/three-digit number by the single digit from right to left.
2×4=83×4=121×4=4
Place the 8 in the ones column.
2\times4=8
Place the 2 in the tens column and carry the one.
Add the carried 1 and place 5 in the final column.
132×4=528
Note: Mental methods such as partitioning, breaking down and taking away from a round number can also be used for multiplication involving a three-digit number and a one-digit number.