26 Nov 2006
Have you sussed out how it works ? Lets suppose you choose your 2 digit number as 'ab'. Its numeric value = 10a + b Now add the digits = a + b Now subtract them = 10a + b - (a + b) = 10a + b - a - b = 9a So the answer is always a multiple of 9: 9, 18, 27, 36, etc. You'll notice that multiples of 9 a...