Building speed

How to get quicker without drilling for hours.

Short and often

Five minutes a day beats an hour a week, because the goal is recall rather than technique. Use real numbers from shopping, bills and timings so the practice has a purpose.

Say the running total out loud or under your breath. It keeps the number in place.
When you get one wrong, redo it slowly rather than moving on.

Know when to stop

Mental arithmetic is for judgement and small sums. Anything with money, many steps or real consequences deserves a calculator and a second look.