AN N1/E2.1 Count reliably to 100, count on in 2s and 10s
Count reliably up to 100 items (a) Count in twos and tens up to 100 (b) Count on in tens up to 100, starting from any two-digit number
Adult Numeracy Core Curriculum, Basic Skills Agency / DfEE (2001, 2006): https://www.excellencegateway.org.uk/content/etf1075