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Grade 7 Maths: Whole numbers: properties and calculations poster

A one-page CAPS Grade 7 Maths poster on whole numbers: properties and calculations (Numbers), with the key ideas, key words and a tip to remember.

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Maths · Grade 7 · Numbers

Whole numbers: properties and calculations

1Place value and rounding

Each place is worth 10 times the place to its right. To round, look at the digit to the right. 5 or more rounds up.

Example

The 8 in 382 570 416 is worth 80 000 000.
36 748 to the nearest 100 is 36 700.

Commutative: the order does not matter for + and ×. 9 + 4 = 4 + 9
Associative: the grouping does not matter for + and ×. (2 × 3) × 5 = 2 × (3 × 5)
Distributive: a × (b + c) = a × b + a × c
Identity: adding 0 or multiplying by 1 changes nothing.

Break a number into easy parts to calculate in your head.

Example

7 × 98 = 7 × 100 − 7 × 2
= 700 − 14 = 686
6 × 204 = 6 × 200 + 6 × 4 = 1 224

Example

1 236 × 23 = 1 236 × 20 + 1 236 × 3
= 24 720 + 3 708 = 28 428

Brackets, then exponents, then × and ÷ from left to right, then + and − from left to right.

Example

30 − 4 × (2 + 3)
= 30 − 4 × 5 = 30 − 20 = 10

Round the numbers first. If your answer is far from the estimate, check again.

Example

5 912 × 28 is about 6 000 × 30 = 180 000

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