Estimating and approximating

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

Can you rank these sets of quantities in order, from smallest to largest? Can you provide convincing evidence for your rankings?

How many ways can you find to put in operation signs (+, −, ×, ÷) to make 100?

These Olympic quantities have been jumbled up! Can you put them back together again?

My measurements have got all jumbled up! Swap them around and see if you can find a combination where every measurement is valid.

Here's a chance to work with large numbers...

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

Have you ever wondered what it would be like to race against Usain Bolt?

Use your skill and knowledge to place various scientific lengths in order of size. Can you judge the length of objects with sizes ranging from 1 Angstrom to 1 million km with no wrong attempts?