Maths on the Back of an Envelope

{"strong"=>["‘Another terrific book by Rob Eastaway’ SIMON SINGH"]}
{"strong"=>["‘A delightfully accessible guide to how to play with numbers’ HANNAH FRY"]}
How many cats are there in the world?
What's the chance of winning the lottery twice?
And just how long does it take to count to a million?
Learn how to tackle tricky maths problems with nothing but the back of an envelope, a pencil and some good old-fashioned brain power.
Join Rob Eastaway as he takes an entertaining look at how to figure without a calculator. Packed with amusing anecdotes, quizzes, and handy calculation tips for every situation, Maths on the Back of an Envelope is an invaluable introduction to the art of estimation, and a welcome reminder that sometimes our own brain is the best tool we have to deal with numbers.