Page 8 - 新思维数学活动用书7 样章
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1.2 Multiplying and dividing integers
15 Copy and complete these addition pyramids.
a b
1 –2 –4
–3 4 6 –1
16 This addition pyramid is more difficult than the pyramids –6
in Question 13.
Copy and complete the pyramid. Explain how you worked 5 3
out the missing numbers.
1.2 Multiplying and dividing integers
Worked example 1.2 Key word
Work out: product
a 4 × −8 b 20 ÷ (−3 + −2)
Answer
a 4 × 8 = 32, so 4 × −8 = −32.
b First, do the addition in the bracket.
−3 + −2 = −5
So, 20 ÷ (−3 + −2) = 20 ÷ −5 = −4.
Exercise 1.2
Focus
1 Work out:
a 10 × −3 b 4 × −9 c 5 × −11 d 7 × −7
2 Work out:
a −24 ÷ 2 b 24 ÷ −6 c −50 ÷ 10 d 63 ÷ −9
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