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# 1.18 Composition and calculation: three-digit numbers

Created on 09 August 2018 by ncetm_administrator
Updated on 10 August 2018 by ncetm_administrator

## Introduction

Explore the composition of three-digit numbers; use place-value and partitioning knowledge to support additive calculation, and extend known additive strategies to three-digit numbers.

## Teaching points

• Teaching point 1: Three-digit numbers can be composed additively from hundreds, tens and ones; this structure can be used to support additive calculation.

• Teaching point 2: Each number on the 0 to 1,000 number line has a unique position.

• Teaching point 3: The smallest three-digit number is 100, and the largest three-digit number is 999; the relative size of two three-digit numbers can be determined by examining the hundreds digits, then the tens digits, and then the ones digits, as necessary.

• Teaching point 4: Three-digit multiples of ten can be expressed multiplicatively and additively, in terms of tens or hundreds.

• Teaching point 5: Known facts and strategies for addition and subtraction within and across ten, and within and across 100, can be used to support additive calculation within 1,000.

• Teaching point 6: Familiar counting sequences can be extended up to 1,000.

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