The sum means the total when the numbers are added together.

Unisiting means treating groups that contain the same number of things as 'ones' or 'units'.

Add two 3-digit numbers using partitioning

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

Which group has a different number of 'units'?

Match the expressions with the most relevant strategy for mental addition.

An addend is a number multiplied by a number.

An addend is a number subtracted from another.

The bucket balance has been filled with marbles and blocks. It is balanced. Which of these most closely represent the equation shown by the bucket balance?

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