Find the following values without a calculator.
For 2 and 5,
- what is the first common multiple?
- what is the second common multiple?
- what is the fourth common multiple?
(a)
Multiples of 2: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50
Multiples of 5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50
First common multiple = 10
(a)
10 x 2 = 20
Second common multiple = 20
(a)
10 x 4 = 40
Fourth common multiple = 40
Answer(s): (a) 10; (b) 20; (c) 40