Question

Richard was born in the 20th century. On his birthday in 2016, his age will be equal to the remainder when his birth year is divided by 100. How old will Richard be on his birthday in 2042?

Answer 1

so, what is the remainder in 2016/100 ?
That will tell you when he was born.

Note: the last year of the 20th century was 2000, not 1999.