240 Pocket Calcudoku

240 Pocket Calcudoku is Calcudoku in a travel-friendly size. Each book holds 240 maths-and-logic puzzles in a compact format that slips into a bag, so it's ideal for holidays, journeys and waiting rooms.

There are four books to choose from. Easy to Hard is a gentle start. Medium to Very Hard suits regular solvers. Hard to Extreme is for experienced solvers who want a challenge on the move. Easy to Extreme mixes every level in one book, so you get a bit of everything, and it makes a good gift when you aren't sure of someone's level.

The rules are classic Calcudoku: fill each row and column with each number once, and make every outlined cage reach its target with +, −, × or ÷. You only need basic arithmetic; the real challenge is the logic of working out which combinations fit.

If you'd prefer bigger grids at home, see 157 Large Print Calcudoku or the full-size 600 Calcudoku series. The pocket books are for the times when you want a good puzzle and only have a small bag.