Grade 4 Mathematics Numbers – Subtraction Notes
Mathematics — Numbers: Subtraction
For learners (age 9) — Kenyan context
What is subtraction?
Subtraction is taking away one number from another. The sentence "12 − 5 = 7" reads: twelve minus five equals seven.
Key words: minuend (number you start with), subtrahend (number you take away), difference (answer).
1. Subtraction using place value (tens and ones)
Split numbers into tens and ones. Example: 56 − 23.
23 = 2 tens and 3 ones
Subtract tens: 5 − 2 = 3
Answer: 33
2. Subtraction with borrowing (regrouping)
When the ones in the minuend are smaller than the ones in the subtrahend, borrow 1 ten (10 ones).
(= 60 + 12)
Subtract tens: 6 − 4 = 2
Answer: 24
Visual using blocks (helps to see tens and ones)
3. Using a number line
Count back on the number line. Example: 43 − 17.
4. Check by addition
If 43 − 17 = 26, check: 26 + 17 = 43. If addition gives the original minuend, subtraction is correct.
Practical Kenyan examples
Example 1 (money): Asha had KES 100. She bought exercise books for KES 37. How much money is left?
100 − 37 = 63. Asha has KES 63 left.
Example 2 (fruits): A vendor had 85 mangoes. He sold 29 mangoes. How many remain?
85 − 29: borrow (85 = 7 tens 15 ones after borrowing) → 15−9=6 ones, 7−2=5 tens → 56 mangoes.
Example 3 (school): A teacher had 48 pencils. She gave 13 to students. 48 − 13 = 35 pencils left.
Tips for learners
- Always line up digits by place value (units under units, tens under tens).
- If you cannot subtract the ones, borrow 1 ten = 10 ones.
- Check your answer by adding the difference and the subtrahend: difference + subtrahend = minuend.
- Use a number line or draw tens/ones blocks if you get stuck.
Practice (try these)
- 64 − 27 = ?
- 51 − 19 = ?
- 90 − 34 = ?
- Amina had KES 250. She bought food for KES 78. How much left?
- 78 − 59 = ?
1) 37 2) 32 3) 56 4) 172 5) 19
Keep practising with items you see daily — coins, books, fruits or chairs. Subtraction becomes easy with place value understanding and practice.