8
Use your calculator to work out the value of 9.232 + 5.34 2 .
a Write down all the figures on your calculator display. b Write your answer to part a correct to 2 significant figures. 9 PS
10
Work out an estimate for 6.13 × 78.8 . 0.405 Mary set up her Christmas tree with two sets of twinkling lights. Set A would twinkle every 4 seconds. Set B would twinkle every 6 seconds. How many times in a minute will both sets be twinkling at the same time?
11
a Use your calculator to work out 355 ÷ 113. Give your answer as a decimal.
b Part a is considered to be the best approximation to π as it is a simple calculation and easy to remember. The accurate value of π is 3.141 592 65 to 8 decimal places. Round your answer to a to 8 decimal places and calculate the percentage error in the approximation given by 355 ÷ 113. PS
12
he Town Hall clock gains two minutes every hour. The clock at the library is T accurate. They both chime on every quarter hour. Both clocks are set at 12:00 noon on Monday so they chime together.
a At what time and day will they next chime together? b At what time and day will they next chime on the hour together? 13
In prime factor form, 240 = 24 × 3 × 5 and 756 = 22 × 33 × 5. Work out, in prime factor form:
a the LCM of 240 and 756 b the HCF of 240 and 756. 14
As a product of prime factors 60 = 22 × 3 × 5.
a What number is represented by 2 × 32 × 5? b Find the lowest common multiple (LCM) of 60 and 48. c Find the highest common factor (HCF) of 60 and 78. MR
15
Jack thinks of two numbers. He says, “The highest common factor (HCF) of my two numbers is 9. The lowest common multiple (LCM) of my two numbers is 108.” Write down two numbers that Jack could be thinking of.
16
0.38
b Is the actual answer higher or lower than the estimate? Explain your answer.
CM PS
a Use approximations to estimate the value of 113 × 8.08 .
17
a p, q and r are prime numbers such that pqr3 = 270. Work out the values of p, q and r.
b Work out the highest common factor of 270 and 105. MR
18
The number 864 can be written as 2m × 3n, where m and n are prime numbers. Find the value of m and the value of n.
1 Review questions
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