KS2 SATs 2025 — Mathematics Papers 2 & 3: Reasoning

The idea

A powerful final habit is asking: does this answer make sense? Estimate before or after you calculate by rounding to friendly numbers. If 28 books cost £6 each, the total should be near 30 × £6 = £180. An answer of £1,680 has the right digits but the wrong size — a place-value slip.

Plausibility checks use real-world sense too. Change cannot be more than the money you handed over, a child's height cannot be 15 metres, and a part cannot be bigger than the whole it came from.

When a question asks you to explain, write the steps as a short story: say what you did, why you did it, and what the result means. A clear explanation can earn marks even when a small slip appears in the final number.

Worked example

A class buys 28 reading books at £6 each. Sam says the total cost is £1,680. Explain why Sam must be wrong, and work out the correct total.

1. Estimate first: 28 is close to 30, and 30 × £6 = £180, so the total should be near £180, not near £1,680.
2. Sam's answer is about ten times too big, so a place-value slip has happened.
3. Calculate exactly: 28 × 6 = 168, so the total is £168.

Answer: £168 — Sam's £1,680 is roughly ten times too large

Watch out

• Accepting an answer just because the digits look familiar, without checking its size.
• Explaining by only writing 'I worked it out', without saying what you actually did.