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Mathematics — Subtraction

Subtopic: Mixed Exercise — Subtraction (Age 7, Kenya)

Subtraction means taking away. We write it as: 12 − 5 = 7

Ways to subtract

Counters (pictures) — use objects like apples or coins.
Number line — count backwards on the line.
Column method — put tens and ones in columns; borrow if needed.

1) Counters (easy visual)

Example: 9 − 4

🍎🍎🍎🍎🍎🍎🍎🍎🍎 (9 apples)
take away 4: 🍎🍎🍎🍎 (remove these) → left: 🍎🍎🍎🍎🍎 = 5

2) Number line

Example: 12 − 5. Start at 12, jump back 5:

      12 → 11 → 10 → 9 → 8 → 7    so 12 − 5 = 7
    

3) Column method (written)

a) No borrowing:

So 64 − 21 = 43

b) With borrowing (show steps)

      Example: 43 − 17

      Step 1: Write columns

         4 3

      −   1 7

      -------

      Step 2: Ones: 3 − 7? cannot, so borrow 1 ten from the 4 tens.

      4 tens becomes 3 tens; ones become 13 ones.

      Now: 13 − 7 = 6 (ones) and 3 − 1 = 2 (tens).

      Answer: 26

Mixed practice (try to work out)

9 − 3
15 − 7
20 − 8
34 − 12
40 − 19
50 − 27
18 − 9
63 − 29
Word problem: Amina has KSh 20. She buys sweets for KSh 7. How much money is left?
Word problem: John had 14 mangoes. He gave 6 mangoes to his friend. How many mangoes left?

Answers (check your work)

9 − 3 = 6
15 − 7 = 8
20 − 8 = 12
34 − 12 = 22
40 − 19 = 21
50 − 27 = 23
18 − 9 = 9
63 − 29 = 34
KSh 20 − KSh 7 = KSh 13 (Amina has KSh 13 left)
14 − 6 = 8 (John has 8 mangoes left)

Tips for learners (Age 7)

Use real objects (stones, pencils, fruits) when you start.
Count back on a number line for small numbers.
When using columns, always line up tens and ones carefully.
If you borrow, remember you take 1 ten and add 10 ones first.
Use Kenyan examples (KSh, school items) to practise story sums.

Good work! Try making your own questions using things at home or at school — e.g., "I had 25 KSh, I bought a pen for 8 KSh. How much left?"

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Topics

Grade 2 Mathematics Subtraction – Mixed Exercise Subtraction Notes