Fast Subtraction Without Losing Track

Subtraction becomes easier when you choose the representation that creates the fewest mental steps.

Round the subtrahend

632 − 298 → 632 − 300 + 2 = 334.

Count up for close numbers

503 − 487: 487→500 is 13, then 500→503 is 3, so the difference is 16.

Subtract in chunks

764 − 231 → 764 − 200 = 564; −30 = 534; −1 = 533.

Estimate first

Before exact calculation, estimate the answer. If 764−231 is roughly 530, an accidental answer of 633 is immediately suspicious.

Educational note: these techniques are practice methods, not medical or cognitive-performance claims.