___________
Maths
Informal and mental strategies for adding and subtracting two 3-digit numbers
Starter quiz
Try it
Give to class
Which of these subtraction expressions can be more efficiently solved by finding the difference?
75 − 68 = ✓
96 − 19 =
32 − 25= ✓
83 − 38 =
What is the missing part in this bar model?
'80' ✓
Match the numbers so that they make a pair with a sum of 100.
20
⇔
80 ✓
40
⇔
60 ✓
75
⇔
25 ✓
95
⇔
5 ✓
Use a find the difference strategy to calculate: 54 − 47 =
______
'7' ✓
Use a partitioning strategy to find the sum of 135 and 270
'405' ✓
Select all the multiples of 10
75
90 ✓
100 ✓
103
150 ✓
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