KS2 SATs 2022 — Mathematics Paper 1: Arithmetic

The idea

When a calculation has several operations, everyone must do them in the same order to get the same answer. BIDMAS gives that order: Brackets first, then Indices (like squaring), then Division and Multiplication, then Addition and Subtraction.

Division and multiplication have equal importance, so work through them from left to right. The same is true for addition and subtraction: equal importance, left to right. Brackets are powerful because anything inside them is worked out before everything else.

A safe method is to rewrite the calculation after each step, replacing the part you have just worked out with its value. Squaring a number means multiplying it by itself, so 3 squared is 3 × 3 = 9, not 3 × 2.

Worked example

Work out 6 + 4 × 3² − 8 ÷ 2.

1. Indices first: 3² = 9, so the calculation becomes 6 + 4 × 9 − 8 ÷ 2.
2. Multiplication and division next: 4 × 9 = 36 and 8 ÷ 2 = 4, giving 6 + 36 − 4.
3. Addition and subtraction last, left to right: 6 + 36 = 42, then 42 − 4 = 38.

Answer: 38

Watch out

• Working strictly left to right and ignoring BIDMAS.
• Thinking 3² means 3 × 2 instead of 3 × 3.