Estimating and approximating

problem
Squaring the circle

Age

11 to 14

Challenge level

Bluey-green, white and transparent squares with a few odd bits of shapes around the perimeter. But, how many squares are there of each type in the complete circle? Study the picture and make an estimate.
problem
Whole numbers only

Age

11 to 14

Challenge level

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

Age

16 to 18

Challenge level

Which is larger: (a) 1.000001^{1000000} or 2? (b) 100^{300} or 300! (i.e.factorial 300)
problem
Ladder and cube

Age

14 to 16

Challenge level

A 1 metre cube has one face on the ground and one face against a wall. A 4 metre ladder leans against the wall and just touches the cube. How high is the top of the ladder above the ground?
problem
What's my weight?

Age

7 to 11

Challenge level

There are four equal weights on one side of the scale and an apple on the other side. What can you say that is true about the apple and the weights from the picture?
problem
Buying a balloon

Age

7 to 11

Challenge level

Lolla bought a balloon at the circus. She gave the clown six coins to pay for it. What could Lolla have paid for the balloon?
page
Building patterns

Can you deduce the pattern that has been used to lay out these bottle tops?
game
Favourite

Dicey operations

Age

7 to 14

Challenge level

In these addition and subtraction games, you'll need to think strategically to get closest to the target.
game
Favourite

Countdown

Age

7 to 14

Challenge level

Here is a chance to play a version of the classic Countdown Game.
problem
Almost one

Age

11 to 14

Challenge level

Choose some fractions and add them together. Can you get close to 1?