In computer courses, sometimes a riddle is given that a person can solve, but not a single machine can solve yet. Here it is.
How old are three sisters if:
Multiplying their ages gives the number 36. Adding their ages gives 13. The eldest is blonde.
Already guessed?
Multiplying their ages gives 36, which is one of the eight following combinations:
36 = 2 × 3 × 6, adding these numbers gives the number 11.
36 = 2 × 2 × 9, adding these numbers gives the number 13.
36 = 4 × 9 × 1, adding these numbers gives the number 14.
36 = 4 × 3 × 3, adding these numbers gives the number 10.
36 = 18 × 2 × 1, adding these digits gives 21.
36 = 12 × 3 × 1, adding these digits gives 16.
36 = 6 × 6 × 1, adding these digits gives 13.
36 = 36 × 1 × 1, adding these numbers gives the number 38.
There are two possible answers, since 2 + 2 + 9 is 13, and so is 6 + 6 + 1.
Note: “The eldest is blonde” – allows you to find out that there is the eldest daughter who does not have a twin. So, only the first formula suits us.
Solution: three sisters – the eldest of nine and two twins of two years.
