Simple one.

There is a number that is 3 times the sum of its digits. What is this number?

just want to bring this to the first page.

-- James.

let us say the number is xy

It is given that
3(x+y) = 10x +y
=> 2y = 7x
=> x/y =2/7

x and y are single digit integers so only possible vlaues of x and y are 2 and 7 respectively.

so the number is 27.

-- James