Dear Parents, we just finished learning how to subtract numbers up to 18 mentally (in our head). Subtraction proved to be a bit more challenging than addition, so please review and practise these strategies with your children. Many students have unfinished subtraction work, so I am sending it home to be completed over the holiday break. Please help your child with applying the strategies, rather than focussing on getting the right answer.
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Subtraction Strategy:
Counting back 1, 2, or 3
When subtracting 1, 2, or 3, start with the greater number and count back.
See: 10 - 2 = See: 11 - 3 =
Think: 10 … 9, 8 Think: 11 … 10, 9, 8
Subtraction Strategy:
Zero Facts
When you take away all, 0 is left.
See: 7 - 7 =
Think: Take away all, 0 is left.
Subtraction Strategy:
Zero Facts
When you take away 0 from any number, the number stays the same.
See: 8 - 0 =
Think: Take away 0, leave all.
Subtraction Strategy:
Doubles
When you subtract half of a number, think of the doubles picture.
See: 14 - 7 = See: 10 - 5 =
Think: days in 2 weeks Think: fingers on each hand
Subtraction Strategy:
Counting Up
When the numbers are close neighbours,
count up.
See: 11 - 9 =
Think: 9…10, 11 à That’s 2.
Subtraction Strategy:
Think Addition
When subtracting from a teen number, think of the related addition fact.
See: 13 - 8 =
Think: 8 + 5 = 13 , so 13 – 8 = 5
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