A soap brand held 15% of a town's market in 2022. In 2023 its market share grew by 40%. By how many percentage points did its share rise?

'Grew by 40%' means the share was multiplied by 1.40, so the new share is $15\times 1.40=21$%. The rise is therefore 21 - 15 = 6 percentage points. '40 percentage points' is the trap of confusing a per cent GROWTH with a rise in percentage POINTS. '21 percentage points' quotes the new share instead of the rise, and '60 percentage points' is $0.40\times 15$ with the decimal point slipped.