You may also like

problem icon


Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

problem icon

Adding All Nine

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!

problem icon

Have You Got It?

Can you explain the strategy for winning this game with any target?

Product 100

Stage: 3 Short Challenge Level: Challenge Level:1

Since $100=2\times2\times5\times5$, the only possible product of four different positive integers which equals $100$ is $1\times2\times5\times10$. The sum of these integers is $1+2+5+10 = 18$.

This problem is taken from the UKMT Mathematical Challenges.