Adam's age is a multiple of 7 this year.
His age 2 years ago was a multiple of 8.
Adam's age is between 40 and 50.
- In how many years' time will Adam's age be a multiple of 4?
- How many years ago was Adam's age a multiple of 9?
(a)
Multiple of 7: 7, 14, 21, 28, 35, 42
Multiple of 7 (-2): 5, 12, 19, 26, 33, 40
Multiples of 8: 8, 16, 24, 32, 40
Adam's age this year = 42
Multiples of 4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44
Number of years' time when Adam will be a multiple of 4
= 44 - 42
= 2
(b)
Multiples of 9: 9, 18, 27, 36
Least number of years ago when Adam's age was a multiple of 9
= 42 - 36
= 6
Answer(s): (a) 2; (b) 6