Addition & Subtraction • Topic 4 of 5

Word Problems

Word problems are where arithmetic meets comprehension, and that is precisely the difficulty: the maths may be easy, but choosing the right operation is not. Children are taught clue words, addition signals like total, altogether, in all, more than, combined, and subtraction signals like left, difference, fewer than, how many more. These help, but NCF 2005 warns that clue words are a guide, not a rule, because context can flip them (more than can mean either add or compare). Underneath the words sit problem structures worth knowing as a teacher: addition splits into part-part-whole (combining two amounts) and additive comparison (one amount is some more than another); subtraction splits into take away, comparison (the gap between two amounts), and missing addend. Bar models, the Singapore approach, are a powerful way to make these structures visible. The harder species is the multi-step problem, which needs two operations in sequence. A fruit seller starts with 120 apples, sells 45 then 38: first add what was sold, 45 + 38 = 83, then subtract from the stock, 120 - 83 = 37. The teaching point is to plan the steps before computing and to check the answer against the story, does 37 apples left make sense.

✅ Solved examples

1. Ravi has 25 marbles. His sister gives him 18 more. How many altogether?
The clue word altogether signals combining, so add: 25 + 18 = 43. Ravi has 43 marbles. This is a part-part-whole addition structure.
2. Seema is 132 cm tall and Meena is 145 cm tall. How much taller is Meena?
This is a comparison, so subtract the smaller height from the larger: 145 - 132 = 13. Meena is 13 cm taller. No clue word here means take away; the word taller signals finding a difference.
3. A fruit seller had 120 apples, sold 45 in the morning and 38 in the evening. How many are left? (multi-step)
Step 1, total sold: 45 + 38 = 83. Step 2, apples left: 120 - 83 = 37. The answer is 37 apples. The first step is addition, the second subtraction.
4. A library has 678 books. 234 are added, then 185 are issued. How many are in the library now? (multi-step)
Step 1, after adding: 678 + 234 = 912. Step 2, after issuing: 912 - 185 = 727. The library now has 727 books.

✏️ Practice — try these, take hints as needed

1. There were 42 birds on a tree and 15 flew away. How many are left?
"Flew away" and "left" signal take away.
Subtract 15 from 42.
27
2. A book costs Rs. 85. A bag costs Rs. 120 more than the book. What does the bag cost?
"More than" here means add to the book price.
85 + 120.
Rs. 205
3. Riya has Rs. 50. She buys a notebook for Rs. 25 and a pen for Rs. 15. How much is left? (multi-step)
First add what she spent.
Then subtract from 50.
Rs. 10 (spent 25 + 15 = 40, then 50 - 40 = 10)
4. A school has 215 boys and 198 girls. If 75 students are absent, how many are present? (multi-step)
Find the total roll first.
Then subtract the absentees.
338 (total 215 + 198 = 413, then 413 - 75 = 338)

📝 Topic test — 8 questions

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