Dozenslive
Age 7 to 14
Challenge Level
Can you select the missing digit(s) to find the largest number?
Take Three from Fivelive
Age 11 to 16
Challenge Level
Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him?
Number Rules - OKlive
Age 14 to 16
Challenge Level
Can you produce convincing arguments that a selection of statements about numbers are true?
Always Perfectlive
Age 14 to 18
Challenge Level
Show that if you add 1 to the product of four consecutive numbers the answer is ALWAYS a perfect square.
Common Divisorlive
Age 16 to 18
Challenge Level
Can you find out what numbers divide these expressions? Can you prove that they are always divisors?
Polite Numberslive
Age 16 to 18
Challenge Level
A polite number can be written as the sum of two or more consecutive positive integers, for example 8+9+10=27 is a polite number. Can you find some more polite, and impolite, numbers?
Digital Equationlive
Age 16 to 18
Challenge Level
Can you find a three digit number which is equal to the sum of the hundreds digit, the square of the tens digit and the cube of the units digit?
Secondary Toughnutslive
Age 11 to 18
Challenge Level
These secondary problems have not yet been solved. Can you be the first?
NRICH is part of the family of activities in the Millennium Mathematics Project.