Number · Integers, powers & roots
Chapter 1 · 3
The idea
Long multiplication, division and calculator skills
Why long multiplication and division work, so you can do them by hand without losing a place value; what a remainder means in a real question; multiplying and dividing decimals; getting new answers from a fact you are given; and keying a calculation in so the calculator does what the question means, then reading its display.
A full journey — read it, play with it, work it, then earn real exam marks. Everything stays on the timeline below.
In this lesson — start anywhere
Number · Integers, powers & roots
Long multiplication, division and calculator skills
Why long multiplication and division work, so you can do them by hand without losing a place value; what a remainder means in a real question; multiplying and dividing decimals; getting new answers from a fact you are given; and keying a calculation in so the calculator does what the question means, then reading its display.
Why it works
Long multiplication: four pieces
The Year 10 stall at the school fair sells biscuits and lemonade, and every sum on this page comes from it. The stall orders boxes of biscuits. How many biscuits is that?is too big to know by heart, so split both numbers into tens and units: and . Picture a rectangle by , cut into four pieces. Each piece is a fact you know:Add them: biscuits. This is the grid method: two parts times two parts makes four pieces. Tens times tens plus units times units, , misses two of them.
Keep reading — free
The rest of the explanation, plus 5 worked examples you step through move by move.
Start freeTakes a minute — no card.