Long multiplication and long division, explained
The written methods for numbers too big for the times tables: multiply by one digit at a time and add the rows, or divide, multiply, subtract and bring down. Decimals need only one extra step each, and it is all about where the point goes.
- How to do long multiplication One row for each digit, then add the rows.
- How to do long division Divide, multiply, subtract, bring down.
- How to multiply decimals Multiply as whole numbers, then count the decimal places.
- How to divide decimals Make the divisor whole, then keep the point in line.
Questions people ask
Does my child need to know the times tables first?
Mostly, yes. Both methods break one big calculation into lots of small ones, and every small one is a times-table fact. A child who has to work out 7 × 8 each time tends to lose their place in the method.
Which comes first, long multiplication or long division?
Long multiplication. Long division uses it at every step, because each digit of the answer is multiplied by the divisor and the result taken away.