CTET · Study & Practice
Addition & Subtraction
Addition and subtraction look deceptively simple, which is exactly why CTET Paper I leans on them so hard. The questions almost never ask you to add two numbers; they ask why a child added them wrong. A pupil who writes 35 + 27 = 512 has not failed arithmetic, she has failed place value, and the paper wants you to spot that. So this chapter works on two levels at once. You need the arithmetic itself watertight, carrying, borrowing across a zero, estimation, the mental shortcuts, and you need the pedagogy underneath it, the language of regrouping, base-ten blocks, the number line, clue words in word problems, and what a wrong answer tells you about a child's thinking. Treat every worked example below as two questions: what is the answer, and what would a seven-year-old get stuck on here.
Topics
1
Addition
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2
Subtraction
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3
Mental Mathematics
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4
Word Problems
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5
Estimation
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⚡ Smart tips & memory hooks
Memory hooks and exam-smart tips to lock this chapter in and answer CTET MCQs quickly and accurately.
- Carry-over and borrowing are the same idea in reverse: 10 ones make 1 ten when adding, 1 ten becomes 10 ones when subtracting.
- Borrowing across a zero: regroup the hundreds first (4 becomes 3, giving 10 tens), then borrow a ten for the ones.
- Check any subtraction instantly: difference + subtrahend must rebuild the minuend.
- For numbers that are close together (203 - 198), count up instead of borrowing.
- Rounding rule in one line: nearest 10 looks at the ones digit, nearest 100 looks at the tens digit; 5 or more rounds up.
- In word problems, read for the structure (combine, take away, compare, missing part), not just the clue word, because context can flip the operation.
⚠️ Common mistakes & traps
CTET loves to test these exact confusions. Internalise each trap before exam day.
- Writing each column total side by side without carrying (26 + 17 = 313 instead of 43) - a place-value error, not carelessness.
- Subtracting the smaller digit from the larger in each column regardless of position (50 - 23 = 33), instead of borrowing.
- Forgetting to reduce the column that was borrowed from by 1.
- Mishandling a zero in the middle of the minuend when borrowing (402 - 135).
- Treating clue words as absolute rules - "more than" can mean add or compare depending on context.
- Rounding to the wrong place: checking the ones digit when rounding to the nearest hundred.
📈 CTET exam insight & PYQ analysis
CTET Paper I Maths draws heavily on numbers and operations, and addition and subtraction items recur in two flavours. The first is the pedagogy-of-error question: a child's wrong working is shown (35 + 27 = 512, or 50 - 23 = 33) and you must diagnose the misconception, almost always place value or failed regrouping. The second is the strategy or concept question: name the mental strategy a child used, identify the correct operation for a word problem, or pick the best estimate. Borrowing across a zero, multi-step word problems, and rounding rules are the highest-frequency exact-computation items. Expect the language of NCF too - the value of children's own methods, estimation as a process, and errors as diagnostic information rather than failure.
🎴 Flashcards — instant recall
Tap a card to reveal the answer. Drill these until they are automatic.
When does carrying happen in addition?Tap to reveal
When a column adds to 10 or more; the ten moves to the next column left.
What does the borrowed 1 represent in subtraction?Tap to reveal
Ten units in the current place value (1 ten = 10 ones).
How do you check a subtraction answer?Tap to reveal
Difference + subtrahend = minuend.
Round to the nearest 10: which digit do you look at?Tap to reveal
The ones digit; 5 or more rounds up.
Round to the nearest 100: which digit do you look at?Tap to reveal
The tens digit; 50 or more rounds up.
Name the strategy: 9 + 6 = 9 + 1 + 5 = 15.Tap to reveal
Making tens (bridging through 10).
Name the strategy: 65 - 19 = 65 - 20 + 1.Tap to reveal
Compensation (round and adjust).
What is the shopkeeper's method?Tap to reveal
Counting up from the smaller number to find a difference (203 - 198 = 5).
A child writes 28 + 15 = 313. What is the error?Tap to reveal
Failed regrouping - column totals written side by side; answer should be 43.
What does the symbol that reads "approximately equal to" tell you?Tap to reveal
The value is an estimate, close but not exact.
List the three meanings of subtraction.Tap to reveal
Taking away, comparing (difference), and finding a missing part.
How should a Piagetian/NCF teacher treat a child's wrong answer?Tap to reveal
As a clue to the child's thinking, not merely a failure to punish.
📌 Quick revision
Addition and subtraction in CTET Paper I are tested as much for pedagogy as for computation. Get the arithmetic watertight: carrying when a column reaches 10, borrowing when the top digit is smaller, and the awkward case of borrowing across a zero, always checking with the inverse (difference + subtrahend = minuend). Know the mental strategies by name - making tens, chunking by place value, doubles, compensation, counting up - because the paper asks you to identify them. For word problems, read the structure (combine, take away, compare, missing part) rather than trusting clue words blindly, and plan multi-step problems before computing. Estimation is a core NCF process: round to the nearest 10 or 100 to judge whether an answer is reasonable. Above all, read a child's wrong answer as a window into place-value understanding, which is the lens behind most questions in this chapter.
Chapter test
📝 Addition & Subtraction — Chapter Test
25 fresh questions · timed · full solutions
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🏆 Vidaara CTET success checklist
You have truly mastered Addition & Subtraction when you can tick every box below.
- Recall every formula in this chapter without looking them up
- Solve each topic’s practice set with at least 80% accuracy
- Use the chapter shortcuts to cut your solving time in half
- Spot and avoid every common trap listed above
- Score 80%+ on the timed chapter test
📋 Chapter mastery scorecard
Track where you stand. Aim for the target before moving to the next chapter.
| Skill checkpoint | Target |
|---|---|
| Concept theory & formulas understood | 100% |
| Topic practice sets attempted (5 topics) | 5/5 |
| Best topic-test score | — → 80%+ |
| Chapter test score | — → 80%+ |
| Flashcards drilled to instant recall | 12 cards |
Key Concepts — Quick Reference
This chapter
Carrying and borrowing (regrouping)
| Carry-over (addition) | Column sum 10 or more: write the ones digit, carry the ten to the next column. |
|---|---|
| Borrowing (subtraction) | Top digit smaller: take 1 from the left column (=10 here), reduce that column by 1. |
| Borrowing across a 0 | No tens to borrow? Take from hundreds first: 4 hundreds, 0 tens becomes 3 hundreds, 10 tens. |
| Check by inverse | Difference + Subtrahend = Minuend, and Sum - one addend = the other addend. |
Estimation and the number line
| Round to nearest 10 | Ones digit 5 or more rounds up, 4 or less stays; ones becomes 0. |
|---|---|
| Round to nearest 100 | Tens digit 50 or more rounds up, 49 or less stays; tens and ones become 0. |
| Front-end estimation | Use leading digits only: 432 + 289 is about 400 + 200 = 600. |
| Number-line jumps | Add by jumping right, subtract by jumping left; bridge through the nearest ten. |