Page 14 - 新思维数学学生用书8 样章

1.2 Multiplying and dividing integers

In this exercise you have:
• used factor trees to write an integer as a product of prime factors

• found the HCF of two integers by first writing each one
as a product of prime numbers
• found the LCM of two integers by first writing each one
as a product of prime numbers.
a Which questions have you found the easiest? Explain why.

b Which questions have you found the hardest? Explain why.

Summary checklist

I can write an integer as a product of prime numbers.

I can find the HCF and LCM of two integers by first writing each one
as a product of prime numbers.

1.2 Multiplying and dividing integers

In this section you will … Key words

• multiply and divide integers, in particular when both brackets
are negative conjecture
• understand that brackets, indices and operations follow inverse

a particular order.
investigate

You can add and subtract any two integers.
For example:

2 + −4 = −2 −2 + −4 = −6 −2 − 4 = −6 −2 − −4 = 2
You can also multiply and divide a negative integer by a positive one.
For example:
2 × −9 = −18 −6 × 3 = −18 −18 ÷ 3 = −6 20 ÷ −5 = −4

In this section you will investigate how to multiply or divide any two
integers. You will use number patterns to do this.

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