What's your age Granny?
A child said that his age in years was equal to the last two digits of his birthyear. The child's grandmother said the same thing.
If they both said it in , how old is the child's grandmother?
The answer is 66.
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1 solution
Let the respective ages of of the child and his grandmother be M and N . It would be evident that a solution to the problem is possible only when the Grandmother was born in the 1 9 th Century and her grandson was born in the 2 0 th century.
Accordingly, we must have:
1 8 0 0 + 2 N = 1 9 3 2 = 1 9 0 0 + 2 M ; giving:
( M . N ) = ( 1 6 , 6 6 ) .
Thus, the respective ages of the child and his grandmother in 1 9 3 2 were 1 6 years and 6 6 years.