# Integers – Chapter 1/Extra Questions for Practice.

**CBSE CLASS 7 MATHEMATICS**

**Integers – Chapter 1.**

E**xtra Questions for Practice**

**Answer the following (2 marks):**

**1. Verify a – (-b) = a + b for the following values of a and b.**

i) a = 25, b = 15

ii) a = 75, b= 20

**2. Write a pair of integers whose sum gives**

i) a negative integer

ii) Zero

**3. Write a pair of integers whose difference gives**

i) a negative integer

ii) zero

**4. In a class test, Manu scored -30, 20, 15 and Sanu scored 20, -15, 25 in three subjects. Who scored more? Can we say that we can add integers in any order?**

**5. Fill in the blanks to make the following statements true:**

i) (-5) + (-7) = ———– + (-5)

ii) 23 + ———- = 0

iii) (3 + (-7)) + (——) = 3 + ((-7) + 5)

**6. What will be the sign of the product if we multiply together**

i) 8 negative integers and 3 positive integers?

ii) 5 negative integers and 4 positive integers?

**7. Find the product**:

i) (-1) x (-2) x (-5) x (-6)

ii) (-876) x (-1)

**8. Replace the blank with an integer to make it a true statement.**

i) (-4) x ——– = 28

ii) 5 x ———- = – 45

**9. The product (-9) x (-5) x (-6) x (-3) is positive whereas the product**

**(-9) x (-5) x 6 x (-3) is negative. Why?**

**10. Find-**

i) (-36) divided by (-4)

ii) (-100) divided by (20)

**ANSWERS**:

**1. i) a = 25, b= 15**

**LHS = a – (-b) = 25 – (-15) = 25 + 15 = 40.**

**RHS = a + b = 25 + 15 = 40.**

**Therefore, LHS = RHS. So verified.**

**ii) a = 75, b = 20**

**LHS= a- (-b) = 75 – (-20) = 75 + 20 = 95**

**RHS = a + b = 75 + 20 = 95.**

**Therefore, LHS = RHS. So verified.**

**2. i) (-11) + 6 = -5**

**ii) (-6) + (+6) = 0**

**3. i) (-20) –(-4) = (-20) + 4 = -16**

**ii) 6 – 6 =0**

**4. Manu’s score = (-30) +20+15 = 5**

**Sanu’s score = 20 + (-15) +25 = 30**

**Sanu scored more.**

**We can add integers in any order. That is known as Commutative property.**

**Integers are commutative under addition.**

**5. i) (-5) + (-7) = (-7) + (-5)**

**ii) 23 + (-23) = 0**

**iii) [3 + (-7)] +5 = 3 + [(-7) +5]**

**6. i) If the number of negative integers are even, then the product will be positive. In the given question 8 negative integers are there; since 8 is an even number their product will be positive.**

**ii) If the numbers of negative integers are odd, then their product will be negative. In the given question 5 negative integers are there, since 5 is an odd number their product will be negative.**

**7. i) 60 **

**Here number of negative integers are 4; since 4 is an even number their product will be positive. So multiply the numbers and put positive sign.**

**ii) 876**

**Here number of negative integers are 2; since 2 is an even number their product will be positive. So multiply the numbers and put positive sign.**

**8. i) (-4) x (-7) = 28**

**ii) 5 x (-9) = -45**

**9. In (-9) x (-5) x (-6) x (-3), the number of negative integers are 4, since it is even their product will be positive whereas in (-9) x (-5) x 6 x (-3), the number of negative integers are 3, since 3 is odd, their product will be negative.**

**10. i) 9**

**ii) -5**