Transcript Count back to subtract a pair of numbers with one decimal place.

Objective:
• Count back to subtract a pair of numbers
with one decimal place
© Hamilton Trust
Stepping Up Term 2
Week 8 Day 2
The counting back strategy for subtracting whole
numbers can be adapted when subtracting
decimals…
56 - 21
1<
35
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= 35
20 <
56
36
Stepping Up Term 2
Week 8 Day 2
The counting back strategy for subtracting
decimals…
5.6 – 2.1
0.1
<
3.5
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= 3.5
2
<
5.6
3.6
Stepping Up Term 2
Week 8 Day 2
How could we adapt the strategy for calculating
75 – 19 to help with 7.5 -1.9 ?
7.5 – 1.9
= 5.6
-2
+0.1
>
5.5
<
7.5
5.6
© Hamilton Trust
Stepping Up Term 2
Week 8 Day 2
How could we use the strategy of ‘bridging’
to help with 5.3 - 0.7 ?
5.3 – 0.7
= 4.6
0.4
<
4.6
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0.3
<
5
Stepping Up Term 2
5.3
Week 8 Day 2
Have a go at applying those strategies to
solve:
© Hamilton Trust
Stepping Up Term 2
Week 8 Day 2
It’s time to earn your stripes…
Aim to be a subtraction sergeant!
4.8 – 0.7
5.6 – 1.3
3.5 – 2.1
3.5 – 2.1
8.3 – 1.9
7.2 – 1.3
7.2 – 1.5
4.5 – 1.8
10.6 – 0.7
Is it easier to count
back a whole number,
then adjust…?
© Hamilton Trust
Stepping Up Term 2
Week 8 Day 2