Numbers, units and arithmetic
Numbers, units and arithmetic

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Numbers, units and arithmetic

3.4.1 Try some yourself

Activity 28

Look at the rules in the boxes above.

Write in your own words the rules for multiplying and dividing, adding and subtracting two numbers, giving an example of each.

Answer

When adding two numbers together, or multiplying two numbers together, it makes no difference which number you write first. You get the same answer either way round.

  e.g. 3 + 4 = 4 + 3, and 3 × 4 = 4 × 3.

When subtracting one number from another or dividing one number by another, it does matter which number you write first. You get different answers the other way round.

  e.g. 8 − 4 = 4 is not the same as 4 − 8 = 4; and 8 ÷ 4 = 2 is not the same as 4 ÷ 8 = 1/2.

Activity 29

Is the following statement true or false?

When adding three numbers together, it doesn’t matter in which order you add them.

Answer

True. For example 2 + 3 + 4 is the same as 4 + 2 + 3.

MU120_4M1

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