4 number facts + - Know 1 fact know 4.

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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 = = = 20 20 – 16 = 4 20 – 4 = 16 = 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 = 20 = 20 = 20 = 20 = 20 = 20 = 20 = 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

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