Adam's age is a multiple of 7 this year.
His age 6 years ago was a multiple of 10.
Adam's age is between 50 and 60.
- 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 5?
(a)
Multiple of 7: 7, 14, 21, 28, 35, 42, 49, 56
Multiple of 7 (-6): 1, 8, 15, 22, 29, 36, 43, 50
Multiples of 10: 10, 20, 30, 40, 50
Adam's age this year = 56
Multiples of 10: 10, 20, 30, 40, 50, 60
Number of years' time when Adam will be a multiple of 10
= 60 - 56
= 4
(b)
Multiples of 5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55
Least number of years ago when Adam's age was a multiple of 5
= 56 - 55
= 1
Answer(s): (a) 4; (b) 1