Adam's age is a multiple of 9 this year.
His age 5 years ago was a multiple of 10.
Adam's age is between 40 and 50.
- In how many years' time will Adam's age be a multiple of 10?
- How many years ago was Adam's age a multiple of 6?
(a)
Multiple of 9: 9, 18, 27, 36, 45
Multiple of 9 (-5): 4, 13, 22, 31, 40
Multiples of 10: 10, 20, 30, 40
Adam's age this year = 45
Multiples of 10: 10, 20, 30, 40, 50
Number of years' time when Adam will be a multiple of 10
= 50 - 45
= 5
(b)
Multiples of 6: 6, 12, 18, 24, 30, 36, 42
Least number of years ago when Adam's age was a multiple of 6
= 45 - 42
= 3
Answer(s): (a) 5; (b) 3