Maths find the missing number

Working at greater Depth .. interim framework - year 2 - solve more complex missing number problems (e.g. 14 + • – 3 = 17; 14 + Δ = 15 + 27)

Working at - recognise the inverse relationships between addition and subtraction and use this to check calculations and work out
missing number problems (e.g. Δ − 14 = 28)

Working towards - use number bonds and related subtraction facts within 20 (e.g. 18 = 9 + ?; 15 = 6 + ?)