4 number facts + - Know 1 fact know 4

= – – = = + + = Learn one, know four 4 + 16 = 20 20 – 16 = 4 Each number sentence can be written in four ways. 20 20 20 20 = – – = 4 + 16 = 20 20 – 16 = 4 20 – 4 = 16 16 + 4 = 20 16 16 16 16 4 4 4 4 = + + =

Learn one, know four 20 – 12 = 8 20 – 12 = 8 20 – 14 = 6 20 – 14 = 6 Can you fill in the gaps? 20 – 12 = 8 20 – 12 = 8 20 – 14 = 6 20 – 14 = 6 20 – 8 = 12 20 – 8 = 12 20 – 6 = 14 20 – 6 = 14 12 + 8 = 20 12 + 8 = 20 6 + 14 = 20 6 + 14 = 20 8 + 12 = 20 8 + 12 = 20 14 + 6 = 20 14 + 6 = 20

Learn one, know four

Learn one, know four 16 – 7 = 9 16 – 7 = 9 16 – 9 = 7 16 – 9 = 7 When you learn one number fact, you are really learning four. What is the missing figure in these? If we learn… 9 + 5 = 14 9 + 7 = 16 9 + 7 = 16 Then we also know… 5 + 9 = 14 14 – 9 = 5 14 – 5 = 9 7 + 9 = 16 7 + 9 = 16 16 – 7 = 9 16 – 7 = 9 16 – 9 = 7 16 – 9 = 7

Learn one, know four