Cambridge International Mathematics

Assumed Knowledge (Number) 25

Example 33 Self Tutor

Estimate the product: 623 £ 69

Round 623 to the nearest 100 and round 69 to the nearest 10.

623 £ 69

¼ 600 £ 70

¼42 000

The estimate tells us the correct answer should have 5 digits in it.

Example 34 Self Tutor

Find the approximate value of 3946 ¥ 79.

3946 ¥ 79 ¼ 4000 ¥ 80

¼ 400 ¥ 8

¼ 50

1 Estimate the products:

a 79 £ 4 b 47 £ 8 c 62 £ 7

d 494 £ 6 e 817 £ 8 f 2094 £ 7

2 Estimate the products using one figure approximations:

a 57 £ 42 b 73 £ 59 c 85 £ 98

d 275 £ 54 e 389 £ 73 f 4971 £ 32

g 3079 £ 29 h 40 989£ 9 i 880 £ 750

3 Estimate using one figure approximations:

a 397 ¥ 4 b 6849 ¥ 7 c 79 095¥ 8

d 6000 ¥ 19 e 80 000¥ 37 f 18 700¥ 97

g 2780 ¥ 41 h 48 097¥ 243 i 798 450¥ 399

In early civilisations, time was measured by regular changes in the sky.

The recurring period of daylight and darkness came to be called aday.

The Babylonians divided the day into hours, minutes and seconds. Ancient

astronomers found the time taken for the Earth to complete one orbit around

the Sun. This became known as ayear.

The base unit of time in the International System of Units is thesecond,

abbreviateds.

I TIME [1.12]

EXERCISE H.3

DEMO

IGCSE01

cyan magenta yellow black

(^05255075950525507595)
100 100
(^05255075950525507595)
100 100
Y:\HAESE\IGCSE01\IG01_AS\025IGCSE01_AS.CDR Wednesday, 10 September 2008 2:12:54 PM PETER
(Page included on the Student CD only)(Page included on the Student CD only)