Redistribution is a way of transforming a sum to make it easier to calculate mentally.

The inverse is the opposite or reverse operation. For example, subtraction is the inverse operation of addition.

Being efficient means finding a way to solve a problem quickly whilst also maintaining accuracy.

Add 2 and 3-digit numbers by redistributing

Maths

In this unit pupils will add and subtract two 3-digit numbers using partitioning, adjusting, redistribution and bridging. In the future unit pupils will accurately and efficiently solve multi-step addition and subtraction problems. They will understand and explain how both addition and subtraction equations can be used to describe the same additive relationship.

In the prior unit pupils found pairs of number that composed 100 and positioned 3-digit numbers on a number line and estimated their position on unmarked number lines. They compared and ordered 3 digit numbers. In this unit pupils will add and subtract two 3-digit numbers using partitioning, adjusting, redistribution and bridging

Informal and mental strategies for adding and subtracting two 3-digit numbers

Use redistribution to find the missing number. {{ }} = 39 + 26

Use redistribution to find the missing number. {{ }} = 530 + 190

Use redistribution to find the missing number. {{ }} = 150 + 397

The base ten representation is showing a calculation being changed. The arrow shows some ones being redistributed. What is the transformed expression going to be?

156 ml of orange juice is mixed with 498 ml of pineapple juice. How many ml of juice is there altogether? {{ }} ml

The total when numbers are added together.

Which of these base ten representations shows 68?

What number is being represented by base ten?

This lesson will be removed by end of Summer Term 2025.

Add 2 and 3-digit numbers by redistributing

Lesson outcome

This lesson will be removed by end of Summer Term 2025.