Mr. P’s Parent Maths Problem of the Week

Last week’s parent problem was taken directly out of this year’s Junior Maths Challenge. You were required to determine sum of certain types of numbers. The trick for this maths problem is being able to figure out exactly which numbers the question is talking about.

On Monday she added all the three-digit numbers each of whose digits is either 0 or 1: As zero cannot be the leading digit in a number, the three-digit numbers made only from 0s and 1s are 100, 101, 110 and 111. Their sum is 422.
On Tuesday she added all the two-digit numbers each of whose digits is either 2 or 3: The two-digit numbers made only from 2s and 3s are 22, 23, 32 and 33. Their sum is 110.
On Wednesday she added her answers from Monday and Tuesday. So, on Wednesday, Ada’s final addition was 422 + 110, which gave her the result of 532.

So the answer is ‘C’.

Problem for Week 2 Term 3