Page 11 - 新思维数学活动用书7 样章

1 Integers

1.3 Lowest common multiples

Worked example 1.3 Key words

Find the lowest common multiple (LCM) of 6 and 9. common multiple
lowest common
Answer multiple (LCM)
The multiples of 6 are 6, 12, 18, 24, 30, 36, You may not need multiple

42, 48, 54, … to list so many
The multiples of 9 are 9, 18, 27, 36, 45, 54, … multiples each time.
The common multiples are 18, 36, 54, …
The lowest common multiple is 18.

Exercise 1.3

Focus

1 Write down the first four multiples of:
a 4 b 7 c 12 d 30
2 How many multiples of 10 are less than 100?
3 a Work out the multiples of 8 that are less than 50.

b Work out the multiples of 5 that are less than 50.
c Write down the lowest common multiple of 8 and 5.
4 a Find the first five common multiples of 2 and 3.

b Copy and complete this sentence:
The common multiples of 2 and 3 are multiples of
c Find the lowest common multiple of 2 and 3.

5 a Write down the first three common multiples of 6 and 4.
b Copy and complete this sentence:
The common multiples of 6 and 4 are multiples of

c Write down the lowest common multiple of 6 and 4.
6 Find the lowest common multiple of:
a 3 and 10 b 4 and 10 c 5 and 10

10