Explaining, convincing and proving

problem

Birthday Party

Age

11 to 14

Challenge level

1 out of 3

The 30 students in a class have 25 different birthdays between them. What is the largest number that can share any birthday?
problem

Old Order

Age

11 to 14

Challenge level

1 out of 3

Who is the youngest in this family?
problem

9 Weights

Age

11 to 14

Challenge level

1 out of 3

You have been given nine weights, one of which is slightly heavier than the rest. Can you work out which weight is heavier in just two weighings of the balance?
problem

Quiz Questions

Age

11 to 14

Challenge level

1 out of 3

Jack does a 20-question quiz. How many questions didn't he attempt?
problem

Out of Line

Age

11 to 14

Challenge level

1 out of 3

Fill in the grid with A-E like a Sudoku. Which letter is in the starred square?
problem

Weekly Lies

Age

11 to 14

Challenge level

1 out of 3

Mr Ross tells truths or lies depending on the day of the week. Can you catch him out?
problem

Distinct Diagonals

Age

11 to 14

Challenge level

1 out of 3

Weekly Problem 21 - 2010
How many diagonals can you draw on this square...
problem

Kept Apart

Age

11 to 14

Challenge level

1 out of 3

The squares of this grid contain one of the letters P, Q, R and S. Can you complete this square so that touching squares do not contain the same letter? How many possibilities are there?
problem

Would You Like a Jelly Baby?

Age

11 to 14

Challenge level

1 out of 3

What is the smallest number of jelly babies Tom must take, to be certain that he gets at least one of each flavour?
problem

Multiplication Magic Square

Age

11 to 14

Challenge level

1 out of 3

Weekly Problem 32 - 2015
Can you work out the missing numbers in this multiplication magic square?