Page 8 - 新思维数学活动用书8 样章

1.2 Multiplying and dividing integers

1.2 Multiplying and dividing integers

Exercise 1.2 Key word

integer
Focus
1 Copy this sequence of multiplications and add three more
multiplications in the sequence.
7 × −4 = −28 5 × −4 = −20 3 × −4 = −12 1 × −4 = −4

2 Work out
a −5 × 8 b −5 × −8
c −9 × −11 d −20 × −6

3 Put these multiplications into two groups.
A −12 × −3 B (−6) 2 C −4 × 9

D 18 × 2 E 9 × −4 F −4 × −9

4 Copy and complete this multiplication table.

× −4 −9

−6
5 −45

−8 −16

5 Work out
a (3 + 4) × 5 b (3 + −4) × 5 c (−3 + −4) × −5 d (3 + −4) × −5

Practice

6 Estimate the answers by rounding numbers to the nearest integer.
a −2.9 × −8.15 b 10.8 × −6.1 c (−8.8) 2 d (−4.09) 2
7 Show that (−6) + (−8) − (−10) = 0
2
2
2
8 This is a multiplication pyramid.
Each number is the product of the two numbers below.
For example, 3 × −2 = −6
a Copy and complete the pyramid. –6
b Show that you can change the order of the numbers on the
3 –2 –1 4
bottom row to make the top number 3456.

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