Methods

Every shortcut the explainer shows you, laid out one at a time — each with a drill that asks for nothing else.

Addition

Make TenAdding a single digit to a number that does not end in zero.47 + 8 = 55 Left-to-Right AdditionAdding anything with more than one digit in it.387 + 245 = 632

Subtraction

Round & AdjustThe number you are taking away ends in 6, 7, 8 or 9.72 − 38 = 34 Left-to-Right SubtractionTaking away a number too far from a round one to be worth rounding.486 − 53 = 433

Multiplication

Multiply by 11Anything times 11.34 × 11 = 374 Multiply by 9Anything times 9 — and it keeps working long after the times table runs out.27 × 9 = 243 Multiply by 5Anything times 5.48 × 5 = 240 Repeated DoublingOne side is 4, 6 or 8 — an even number with a small odd part hiding inside it.37 × 8 = 296 Left-to-Right MultiplicationTwo digits by two digits, when neither side has a shortcut of its own.43 × 27 = 1161

Division

Inverse Times TableThe answer is a single digit.56 ÷ 8 = 7 ChunkingThe answer is bigger than ten.168 ÷ 7 = 24