Make a set of numbers that use all the digits from 1 to 9, once and
once only. Add them up. The result is divisible by 9. Add each of
the digits in the new number. What is their sum? Now try some other
possibilities for yourself!
Is there an efficient way to work out how many factors a large number has?
Hot Pursuit
Age 11 to 14 Challenge Level
I added together the first 'n' natural numbers (positive integers) and was surprised to notice that my answer was a 3 digit number in which all the digits were the same.