You may also like

problem icon

Consecutive Numbers

An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

problem icon

Calendar Capers

Choose any three by three square of dates on a calendar page...

problem icon

Latin Numbers

Can you create a Latin Square from multiples of a six digit number?

Central Sum

Stage: 3 Short Challenge Level: Challenge Level:1

Consider numbers whose first digit is 1. Looking at each possible value for the second digit we find 9 such numbers.

110, 121, 132, 143, 154, 165, 176, 187, 198.

Similarly there are 8 numbers starting with 2; 7 numbers starting with 3...

Lastly there is only one number starting with 9: 990.

Hence the total is 9+8+7+6+5+4+3+2+1 = 45.

This problem is taken from the UKMT Mathematical Challenges.