You may also like

Double Digit

Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. Try lots of examples. What happens? Can you explain it?

Not a Polite Question

When asked how old she was, the teacher replied: My age in years is not prime but odd and when reversed and added to my age you have a perfect square...

Whole Numbers Only

Can you work out how many of each kind of pencil this student bought?

Seven Up

Age 11 to 14
Challenge Level

The number 27 is special because it is three times the sum of its digits

27 = 3 (2 + 7).

Find some two digit numbers that are SEVEN times the sum of their digits (seven-up numbers)?

Are there any three digit 'seven-up' numbers. Is it possible to find a number K such that there is a three digit number that is K times the sum of its digits (a K-up number)?