Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
Integers -- Exercise Solutions
Use this page alongside the official Samacheer Kalvi textbook. Solve each exercise first, then check the methods below.
Exercise 2.1 -- Fill in the Blanks (Q1)
Exercise 2.1 -- True or False (Q2)
Q2(i). Each of the integers -18, 6, -12, 0 is greater than -20.
Q2(ii). -1 is to the right of 0.
Q2(iii). -10 and 10 are at equal distance from 1.
| Answer: False -- Distance from 1 to 10 = | 10 - 1 | = 9, but distance from 1 to -10 = | 1 - (-10) | = 11. The distances are not equal. |
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Q2(iv). All negative integers are greater than zero.
Q2(v). All whole numbers are integers.
Exercise 2.1 -- Number Line Questions (Q3, Q4)
Q3. Mark the numbers 4, -3, 6, -1 and -5 on the number line.
Arrange from left to right: -5, -3, -1, 0, 4, 6. Place each integer at equal intervals on the number line.
Q4(i). On the number line, which number is 4 units to the right of -7?
Step-by-step:
- Moving 4 units to the right means adding 4: -7 + 4 = -3
Q4(ii). On the number line, which number is 5 units to the left of 3?
Step-by-step:
- Moving 5 units to the left means subtracting 5: 3 - 5 = -2
Exercise 2.1 -- Opposites (Q5)
Find the opposite of each integer:
| Sub-question | Integer | Opposite |
|---|---|---|
| 5(i) | 44 | -44 |
| 5(ii) | -19 | 19 |
| 5(iii) | 0 | 0 |
| 5(iv) | -312 | 312 |
| 5(v) | 789 | -789 |
The opposite (additive inverse) of any integer n is -n. Zero is its own opposite.
Exercise 2.1 -- Real-Life Situations (Q6)
Q6. If 15 km east of a place is denoted as +15 km, what is the integer that represents 15 km west of it?
Step-by-step:
- East is positive (+); west is the opposite direction, so it is negative (-).
- 15 km west = -15 km
Exercise 2.1 -- Integers Between Given Numbers (Q8)
The integers "between" exclude the endpoints. Count carefully when negatives are involved.
Exercise 2.1 -- Comparing Integers (Q9)
Put the appropriate sign (<, >, or =):
| Sub-question | Comparison | Answer | Reason |
|---|---|---|---|
| 9(i) | -7 ? 8 | -7 < 8 | Negative < positive |
| 9(ii) | -8 ? -7 | -8 < -7 | -8 is further left on the number line |
| 9(iii) | -999 ? -1000 | -999 > -1000 | -999 is closer to zero |
| 9(iv) | -111 ? -111 | -111 = -111 | Same integer |
| 9(v) | 0 ? -200 | 0 > -200 | Zero is greater than any negative |
Rule: On the number line, the integer to the right is always greater. Any positive integer is greater than any negative integer.
Exercise 2.1 -- Ascending Order (Q10)
Q10(i). Arrange in ascending order: -11, 12, -13, 14, -15, 16, -17, 18, -19, -20
Step-by-step:
- Separate negatives: -11, -13, -15, -17, -19, -20
- Sort negatives ascending: -20, -19, -17, -15, -13, -11
- Separate positives: 12, 14, 16, 18
- Sort positives ascending: 12, 14, 16, 18
- Combine: -20, -19, -17, -15, -13, -11, 12, 14, 16, 18
Q10(ii). Arrange in ascending order: -28, 6, -5, -40, 8, 0, 12, -1, 4, 22
Q10(iii). Arrange in ascending order: -100, 10, -1000, 100, 0, -1, 1000, 1, -10
Exercise 2.1 -- Descending Order (Q11)
Q11(i). Arrange in descending order: 14, 27, 15, -14, -9, 0, 11, -17
Q11(ii). Arrange in descending order: -99, -120, 65, -46, 78, 400, -600
Q11(iii). Arrange in descending order: 111, -222, 333, -444, 555, -666, 7777, -888
Exercise 2.1 -- Objective Type Questions (Q12-Q16)
Q12. There are ___ positive integers from -5 to 6. Positive integers: 1, 2, 3, 4, 5, 6
Q13. The opposite of 20 units to the left of 0 is: 20 units left of 0 = -20. Opposite of -20 = 20.
Q14. One unit to the right of -7 is: -7 + 1 = -6
Q15. 3 units to the left of 1 is: 1 - 3 = -2
Q16. The number which determines marking the position of any number to its opposite on a number line is: Zero is the reference point from which opposites are measured.
Exercise 2.2 -- Miscellaneous Practice Problems
Q1. Write two different real life situations that represent the integer -3.
- (i) A temperature of 3 degrees below 0 degrees Celsius (-3 degrees C)
- (ii) A loss of Rs. 3 in a business transaction (-3 rupees)
- (iii) 3 metres below sea level (-3 m)
Q2(i). Mark all integers greater than -7 but less than 7.
Q2(ii). Mark the opposite of 3.
Q2(iii). 5 units to the left of -1.
Step-by-step:
- -1 - 5 = -6
Q3. Construct a number line that shows the depth of 10 feet from the ground level and its opposite.
Step-by-step:
- Ground level = 0
- Depth of 10 feet = -10
- Opposite (height above ground) = +10
Q4. Identify the integers that are at a distance of 8 units from -6.
Step-by-step:
- Going 8 units to the right: -6 + 8 = 2
- Going 8 units to the left: -6 - 8 = -14
Q7. Find the integers that are 4 units to the left of 0 and 2 units to the right of -3.
Step-by-step:
- 4 units to the left of 0: 0 - 4 = -4
- 2 units to the right of -3: -3 + 2 = -1
Exercise 2.2 -- Challenge Problems
Q8. Is there the smallest and the largest number in the set of integers? Give reason.
Q10. P, Q, R, S puzzle on a number line.
Step-by-step:
- (ii) R = smallest positive integer = 1
- (iv) Q = 2 units left of R = 1 - 2 = -1
- (iii) P and S are at the same distance from 0, so they are opposites
- (i) S is the least integer = -2, therefore P = 2
Q11. Place mapping on number line (Home = 0):
| Place | Calculation | Integer |
|---|---|---|
| Home | Starting point | 0 |
| Bus Stand | 3 km right | 3 |
| Library | 2 km left | -2 |
| Dept. Store | 6 km left | -6 |
| Post Office | 1 km right of Library = -2 + 1 | -1 |
| Park | 1 km right of Dept. Store = -6 + 1 | -5 |
| Railway Station | 3 km left of Post Office = -1 - 3 | -4 |
| School | 8 km right of Railway Station = -4 + 8 | 4 |
| Playground | Opposite of Library = -(-2) | 2 |
| Electricity Board | Equal distance from Home as Dept. Store | 6 |
Additional Questions
Q1. Write all the integers between -5 and 10.
Q2. Write the opposite of each:
- (a) Profit of Rs. 500 --> Loss of Rs. 500
- (b) Deposit of Rs. 2000 --> Withdrawal of Rs. 2000
- (c) 50 km towards south --> 50 km towards north
Q5. Write the following numbers with appropriate signs:
- (a) 100 m below sea level = -100 m
- (b) 25 degrees C above 0 degrees C = +25 degrees C
- (c) Any 3 numbers less than 0 = -1, -2, -3
Q7. Draw a number line and answer:
Step-by-step: -2 + 4 = 2
Step-by-step: 1 - 5 = -4
- (a) Which number will we reach if we move 4 numbers to the right of -2?
- (b) Which number will we reach if we move 5 numbers to the left of 1?
- (c) If we are at -8, in which direction should we move to reach -13?
- (d) If we are at -6, in which direction should we move to reach -1?
Q8. Write four negative integers greater than -15 and four negative integers less than -5.
- (a) Four negative integers greater than -15: -11, -10, -5, -1
- (b) Four negative integers less than -5: -7, -15, -18, -20
Q10. Represent the following as integers:
- (a) A deposit of rupees two thousand = +2000
- (b) An aeroplane is flying at a height of three thousand metres above the ground = +3000
Common Mistakes to Avoid
1. Confusing the direction on the number line: On the number line, integers increase to the right and decrease to the left. A common error is treating -7 as greater than -3 because 7 > 3. Remember: -3 > -7.
2. Forgetting zero is an integer: Zero is neither positive nor negative, but it is an integer. When counting "integers from -5 to 5," include 0. Total = 11, not 10.
3. Wrong opposite of negative numbers: The opposite of -5 is 5, not -5. The opposite of a negative integer is positive, and vice versa.
4. Counting endpoints when asked for "between": "Integers between -5 and 5" does NOT include -5 and 5. The answer is -4, -3, -2, -1, 0, 1, 2, 3, 4.
5. Mixing up predecessor and successor: The predecessor of 3 is 2 (3 - 1), not 4. The successor of -5 is -4 (-5 + 1), not -6.
6. Treating "greater" and "more to the right" differently: On the number line, greater always means more to the right. Zero is greater than every negative integer.
| 7. Forgetting that distance is always positive: The distance between -3 and 5 is | 5 - (-3) | = | 8 | = 8, not -8. Distance cannot be negative. |
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Exam Checklist
- [ ] Can you define integers and distinguish them from whole numbers and natural numbers?
- [ ] Can you represent integers on a number line correctly?
- [ ] Can you find the opposite (additive inverse) of any integer?
- [ ] Can you compare integers using <, >, and = signs?
- [ ] Can you arrange integers in ascending and descending order?
- [ ] Can you find integers between two given integers (inclusive and exclusive)?
- [ ] Can you move left (subtract) and right (add) on the number line?
- [ ] Can you represent real-life situations (temperature, altitude, profit/loss) as integers?
- [ ] Can you find integers at a given distance from another integer?
- [ ] Can you identify the predecessor and successor of any integer?
