You may also like

problem icon

Human Food

Sam displays cans in 3 triangular stacks. With the same number he could make one large triangular stack or stack them all in a square based pyramid. How many cans are there how were they arranged?

problem icon

Sam Again

Here is a collection of puzzles about Sam's shop sent in by club members. Perhaps you can make up more puzzles, find formulas or find general methods.

problem icon

Hot Pursuit

I added together the first 'n' positive integers and found that my answer was a 3 digit number in which all the digits were the same...

Forgotten Number

Age 11 to 14 Challenge Level:

The factorials are:

1,
2 x 1 = 2,
3 x 2 x 1 = 6,
4 x 3 x 2 x 1 = 24,
5 x 4 x 3 x 2 x 1 = 120,
6 x 5 x 4 x 3 x 2 x 1 = 720....

The 3 digit numbers less than 500 which are sums of consecutive factorials are:
144, 150, 152 and 153.

The only one of these numbers which satisfies the condition that it is equal to the sum of the cubes of its digits is 153 because 153 = 1 + 125 + 27 so this must be the forgotten number. The information about triangular numbers was not needed but it is easily checked that 153 is a triangular number.

An excellent solution was recieved from Ben from Methwold High School.