Page 33 - Cambridge+Checkpoint+Mathematics+Coursebook+9

End-of-unit review

End-of-unit review

1 Work these out mentally.
a 7 × 0.3 b 15 × 0.4 c 21 × 0.03 d 0.06 × 6 e 0.05 × 20
f 8 ÷ 0.4 g 49 ÷ 0.7 h 30 ÷ 0.1 i 3 ÷ 0.05 j 55 ÷ 0.11

2 Work these out mentally.
a 0.8 × 0.2 b 1.5 × 0.3 c 0.22 × 0.4 d 0.04 × 2.5 e 0.08 × 0.02
f 0.8 ÷ 0.2 g 0.21 ÷ 0.3 h 0.32 ÷ 0.08 i 0.35 ÷ 0.07 j 2.4 ÷ 0.03

3 a Work these out mentally.
i 4 × 0.1 ii 4 × 0.2 iii 4 × 0.3 iv 4 × 0.4 v 4 × 0.5
b Use your answers to part a to answer this question.
If you multiply a number by 0.8, would the answer be larger or smaller than the answer when you
multiply the same number by 0.4?
4 a Work these out mentally.
i 15 ÷ 0.1 ii 15 ÷ 0.2 iii 15 ÷ 0.3 iv 15 ÷ 0.4 v 15 ÷ 0.5
b Use your answers to part a to answer this question.
If you divide a number by 0.8, would the answer be larger or smaller than the answer when you
divide the number by 0.4?

5 Work these out. Remember:
a 9 × 10 b 3.7 × 10 c 24 × 10 d 5.55 × 10 e 7.5 × 10 −2
2
0
3
0
f 5340 ÷ 10 g 2 ÷ 10 h 0.1 ÷ 10 i 62 ÷ 10 j 0.076 ÷ 10 −3 10 = 1
−1
2
0
10 = 10
1
6 Anders says that if you multiply a number by 10 , the answer would be smaller
−3
−4
than the answer you find when you multiply the number by 10 .

Is Anders correct? Give an example to show your answer is true.
7 Round each number to the given degree of accuracy.
a 2.83 (1 d.p.) b 11.859 (2 d.p.) c 0.555 44 (3 d.p.) Remember:
d 0.298 11 (2 d.p.) e 0.123 456 (4 d.p.) f 111.999 99 (3 d.p.) s.f. = signifi cant fi gures
g 105.45 (1 s.f.) h 234.511 (2 s.f.) i 0.654 (2 s.f.) d.p. = decimal places
j 0.018 831 (1 s.f.) k 0.9999 (3 s.f.) l 1.011 (2 s.f.)
8 Round the number 3893.009 561 to the stated degree of accuracy.
a 1 s.f. b 2 s.f. c 3 s.f. d 4 s.f. e 5 s.f.
f 1 d.p. g 2 d.p. h 3 d.p. i 4 d.p. j 5 d.p.

9 Work these out.
30
a 20 − 4 × 4 b 10 × 3 + 3 c 40 − 10 d 100 − 6 × 5 e 6 × 6 − 5 × 5
2
f 40 − 60 g 5(23 − 21) h 5 + 3 j 3 + 4 k 10 − 2(22 + 28)
2
2
2
2
8 10
10 Work out the value of each expression when x = 5 and y = 3.
a 5x − y b 2y + 4x c (x + 2y) d 10(x − 6y) 2
2
2
2
2

32 3 Place value, ordering and rounding