---
title: "Mental calculation strategies"
description: "Perform mental calculations including with mixed operations and large numbers, using strategies such as partitioning, compensation, and derived facts"
canonical: https://lightmysky.com/learn/mathematics/mental-calculation-strategies-mt_vmW2cb5c7A
source: https://lightmysky.com/learn/mathematics/mental-calculation-strategies-mt_vmW2cb5c7A.md
retrieved: 2026-10-19
---

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# Mental calculation strategies

Perform mental calculations including with mixed operations and large numbers, using strategies such as partitioning, compensation, and derived facts

Subject: Mathematics · Area: Multiplication & Division · Ages 10 to 11
Page: https://lightmysky.com/learn/mathematics/mental-calculation-strategies-mt_vmW2cb5c7A

## Ready when they can

- Mentally compute 45 × 8 by partitioning into 40 × 8 + 5 × 8
- Use known facts to derive 6.5 × 4 mentally
- Solve a multi-operation mental calculation such as 250 × 3 + 500 and explain the strategy used

## Lesson: Mental maths: breaking big problems apart

At the till with no calculator, you still need to know what six packs at 52p each will cost before you pay. Mental maths asks you to do that job in your head, by breaking one hard problem into smaller, friendlier ones.

*(drawing: Split 52 into 50 + 2. Multiply each part, then add the results: 300 + 12 = 312.)*

**Example.** To work out 52 × 6 in your head: split 52 into 50 + 2. Work out 50 × 6 = 300 and 2 × 6 = 12. Add them together: 300 + 12 = 312. When one problem has both multiply and add or take away, do the multiply part first.

**Tip.** Derived facts save you work. If you already know 6 × 4 = 24, you don't need to start over for 6.5 × 4. Just add half of 4, which is 2, so 6.5 × 4 = 26.

**Tip.** When a problem has more than one step, like 250 × 3 + 500, do the multiplication first, then the addition. Say each step out loud so you don't lose track: 750, then 750 + 500 = 1250.

**Recap.** Split a hard problem into easy pieces, use facts you already know, and take one step at a time.

## Practice

18 questions on this page, each with its working shown.

## Needs first

- [Mental multiplication and division (age 9+)](https://lightmysky.com/learn/mathematics/mental-multiplication-and-division-age-9-mt_8A3pZNOp7Z)
- [Mental addition and subtraction (age 9+)](https://lightmysky.com/learn/mathematics/mental-addition-and-subtraction-age-9-mt_MWXPiaTnEu)
- [Long multiplication (age 10+)](https://lightmysky.com/learn/mathematics/long-multiplication-age-10-mt_XLP1IM3Qbb)

## Opens up

- [Using a Calculator Well](https://lightmysky.com/learn/mathematics/using-a-calculator-well-mt_FZE80D2jS_)