Mathematics Calculations Policy

Mathematics Calculations Policy

St Blaise Church of England Primary School

Achieving excellence together

First Issue:    Date of Review:

Headteacher:

Chair of Governors:

Introduction

At school children are introduced to the processes of calculation through practical, oral and mental activities. As children begin to understand the underlying ideas, they develop ways of recording to support their thinking and calculation methods.

The overall aim is that when children leave primary school they:

• have a secure knowledge of number facts and an understanding of the four operations;

• are able to use this knowledge and understanding to carry out calculations mentally and to apply general strategies when using one-digit and two-digit numbers and particular strategies to special cases involving bigger numbers;

• make use of diagrams and informal notes to help record steps and part answers when using mental methods that generate more information than can be kept in their heads;

• have an efficient, reliable, written method of calculation for each operation;

• use a calculator effectively, using their mental skills to monitor the process and check the steps involved.

At children will develop a range of mental calculation strategies and be able to apply these to real life problems.

Introduction to mental methods of calculation

Oral and mental work in mathematics is essential, particularly so in calculation. Early practical, oral and mental work must lay the foundations by providing children with a good understanding of numbers, efficient counting strategies and a secure knowledge of place value and number facts.

Introduction to written methods of calculation

The aim is that by the end of Year 6, the great majority of children should be able to use an efficient method for each operation with confidence and understanding.

Addition Calculation Strategies

To add successfully, children need to be able to recall addition pairs to 9 + 9 and complements in 10, add mentally a series of one-digit numbers, add multiples of 10 or 100, and partition two-digit and three-digit numbers into multiples of 100, 10 and 1.

Progression in use of number line

Number track and number lines:

• Number track: 1 2 3 4 5 6 7 8 9 10 11 12

• Number line, all numbers labelled: 0 1 2 3 4 5 6 7 8 9 10 11

• Number line, 5s and 10s labelled: 0 5 10 15 20 25 30 35 40 45 50

• Number lines, 10s labelled: 0 10 20 30 40 50 60 70 80 90 100

• Empty number line

Subtraction Calculation Strategies

The aim is that children use mental methods when appropriate but, for calculations that they cannot do in their heads, they use an efficient written method accurately and with confidence.

Multiplication Calculation Strategies

The aim is that children use mental methods when appropriate, but for calculations that they cannot do in their heads, they use an efficient written method accurately and with confidence.

Division Calculation Strategies

The aim is that children use mental methods when appropriate but, for calculations that they cannot do in their heads, they use an efficient written method accurately and with confidence.

Got a calculation to do?

Mental Calculation Strategy Examples

1. Counting on or back: using a number line we can add by counting on or subtract by counting back.

2. Re-ordering numbers: start with the biggest number when adding, before counting on.

3. Partitioning: shown on a number line or using jottings.

4. Bridging: partition numbers to jump through friendly numbers on a number line.

5. Adjusting: numbers ending in 9 can be changed into friendly numbers and then adjusted.

6. Doubling and near doubling: use partitioning to double 2-digit numbers and adjust for near doubles.