Long Multiplication, Step by Step

The column method and the grid method, both worked out on your own numbers

Long multiplication is not one calculation, it is a handful of small ones added together. This shows both standard ways of laying that out on whatever numbers you enter — the column method, which stacks partial products, and the grid method, which splits both numbers by place value first. Neither is better; they are the same arithmetic arranged differently.

Frequently asked questions

How do you do long multiplication?

Multiply the top number by each digit of the bottom number in turn, starting from the units, shifting each partial product one place further left, then add the partial products together.

Why do you add a zero when multiplying by the tens digit?

Because that digit stands for tens, not units. Multiplying by the 2 in 23 is really multiplying by 20, so the partial product is ten times bigger and shifts one place left.

What is the grid method?

Split both numbers into their place values — 47 into 40 and 7 — multiply every part by every part, then add all the products. It is the same arithmetic as the column method with nothing hidden.

How can I check a long multiplication?

Estimate with rounded numbers to check the size, and check that the last digit of your answer matches the two units digits multiplied together.

Do I need to know my times tables for this?

Yes — every partial product is a times-table fact. If those are slow, long multiplication is slow no matter how well the layout is understood.