# Objectives: Subtract pairs of two‐digit numbers by counting back or counting up; Choose when to use each strategy with simple calculations. © Hamilton.

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Objectives: Subtract pairs of two‐digit numbers by counting back or counting up; Choose when to use each strategy with simple calculations. © Hamilton Trust Stepping Up Term 1 Week 3 Day 3

When is it easier to subtract by counting back? 76 – 21 84 – 32 58 – 34 84 - 30 is 54, then -2 = 52 76 - 20 = 56, then -1 = 55 58 - 30 is 28, then -4 = 24

© Hamilton Trust Stepping Up Term 1 Week 3 Day 3 Lets do a few together… Subtract 33 from each of these 2-digit numbers:

© Hamilton Trust Stepping Up Term 1 Week 3 Day 3 Have you got it? Count back to subtract 21 from the splatted numbers. Do as many as you can in 1 minute!

© Hamilton Trust Stepping Up Term 1 Week 3 Day 3 So, would you use counting up or counting back to solve these subtractions…? 42 – 38 56 – 31 85 – 23 83 – 55 79 – 46 52 – 29 count up count back

© Hamilton Trust Stepping Up Term 1 Week 3 Day 3 It’s no different when using 3-digit numbers… 102 – 97 304 – 297 356 – 201 434 – 220 203 – 189

The white cell shows the difference between the blue and red numbers. Copy and complete one of the grids, choosing to use counting up or counting back for each subtraction. © Hamilton Trust Stepping Up Term 1 Week 3 Day 3 - 35491424 7965 92 68 53 - 1352821443 59 192 77 353310

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