You may also like

problem icon

Counting Factors

Is there an efficient way to work out how many factors a large number has?

problem icon

Summing Consecutive Numbers

15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?

problem icon

Helen's Conjecture

Helen made the conjecture that "every multiple of six has more factors than the two numbers either side of it". Is this conjecture true?

Magic Crosses

Age 7 to 14 Challenge Level:
You can use the magic cross tester below to find magic crosses of your own.
Choose five numbers and put them in the blue boxes.
A message will appear to tell you whether your cross is magic.

Press the reset button to start again.
Reset