Doubling &
Halving
The interactive edition for ages 7–10 (Year 3 to Year 5): nine mental-maths tricks built from two moves — double and halve. × and ÷ by 2, 4, 8, 5, 25 and 50, and tables past 12, typed on a keypad and marked instantly, with how? steps and endless fresh practice. Same sums as the printed book.
