Page 18 - Maths Skills - 7

16 Maths

6. Division by Itself: When a non-zero integer is divided by itself, the quotient is 1.

In other words, if a is any non-zero integer, then a ÷ a = 1
For example; (i) 5 ÷ 5 = 1 (ii) (– 10) ÷ (– 10) = 1

Let’s Attempt

Example 1: Divide the following.
(i) (56) by (– 14) (ii) (– 64) by (– 8)

Solution: (i) | 56 | = 56 and | – 14 | = 14. (ii) | – 64 | = 64 and | – 8 | = 8.
\ 56 ÷ 14 = 4 \ 64 ÷ 8 = 8

Since, the integers are of different signs, Since, the integers are of same signs,
the sign of the quotient is negative. the sign of the quotient is positive.

56 ÷ (– 14) = – 4 \ (– 64) ÷ (– 8) = 8

Example 2: An elevator descends into a mine shaft at the rate of 8 m per min. If the descent starts from 16 m
above the ground level, how long will it take to reach –240 m?

Solution: Total distance to be covered = 16 m – (– 240 m) = 256 m
Elevator descends at the rate of 8 m per min
(240 16+ )m
\ Required time to reach at – 240 m = = 32 min
8 m /min

Exercise 1.4

1. Find the value.

(i) (– 24) ÷ (– 12) (ii) (– 42) ÷ 14 (iii) 245 ÷ (– 5)

(iv) (– 1836) ÷ (– 9) (v) 57 ÷ 19 (vi) 0 ÷ 23

2. Fill in the blanks.

(i) ___ ÷ (– 1) = 309 (ii) ___ ÷ (– 12) = – 7 (iii) 55 ÷ ___ = – 11
(iv) ___ ÷ (– 35) = 0 (v) ___ ÷ 7 = – 8 (vi) 327 ÷ ___ = – 1

3. State whether the following statements are true or false.

(i) 90 ÷ (– 15) = – 6 (ii) – 9 ÷ (– 9) = 1 (iii) (– 17) ÷ 1 = –1
(iv) (– 121) ÷ 11 = 11 (v) 0 ÷ (– 15) = – 15 (vi) (– 13) ÷ (– 13) = – 1

4. Simplify.

(i) | – 12 ÷ 4 | ÷ | 6 ÷ (– 2)| (ii) | 25 ÷ (– 5) | ÷ | 20 ÷ (– 4) |
(iii) | – 7 | ÷ | 7 | – | – 20 | (iv) | – 14 – 1 – 30 | ÷ | 30 – 25 |

5. Temperature of a room at midnight is –4°C. The room temperature increases at the rate of 2°C per
hour. Find the temperature at 4 a.m. and 12 noon.