Practise your skills of proportional reasoning with this interactive haemocytometer.

Examine these estimates. Do they sound about right?

Estimate these curious quantities sufficiently accurately that you can rank them in order of size

How many generations would link an evolutionist to a very distant ancestor?

Unmultiply is a game of quick estimation. You need to find two numbers that multiply together to something close to the given target - fast! 10 levels with a high scores table.

Work out the numerical values for these physical quantities.

Who said that adding, subtracting, multiplying and dividing couldn't be fun?

There are nasty versions of this dice game but we'll start with the nice ones...

Get some practice using big and small numbers in chemistry.

Analyse these beautiful biological images and attempt to rank them in size order.

How might you use mathematics to improve your chances of guessing the number of sweets in a jar?

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

Work with numbers big and small to estimate and calulate various quantities in biological contexts.

In this twist on the well-known Countdown numbers game, use your knowledge of Powers and Roots to make a target.

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

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. . . .

Sissa cleverly asked the King for a reward that sounded quite modest but turned out to be rather large...

10 graphs of experimental data are given. Can you use a spreadsheet to find algebraic graphs which match them closely, and thus discover the formulae most likely to govern the underlying processes?