Page 28 - Maths Skill - 6

26 Maths

(c) We reach at 2, which is the answer. Thus, – 4 + 6 = 2.

6 steps
Or
– 4 – 3 – 2 – 1 0 1 2 3 4

(a) Reach at (–4) first.
(b) Move 6 steps to the right.

(c) We reach at 2.

(ii) –3 and –4

– 10 – 9 – 8 – 7 – 6 – 5 – 4 – 3 – 2 – 1 0 1 2 3

(a) Reach at (–3) first.
(b) Move four steps to the left of (–3).

(c) We reach at (–7) which is the answer. Thus, – 3 + (– 4) = – 7.

Or
– 8 – 7 – 6 – 5 – 4 – 3 – 2 – 1 0 1 2 3

(a) Reach at (–4).

(b) Move three steps to the left of (–4).
(c) We reach at –7.

ADDITION OF INTEGERS WITHOUT USING A NUMBER LINE
Rules of Addition of Integers
Rule I: If two positive or negative integers are added, we add their magnitudes (absolute value) and give common
sign to their sum.
Fact-o-meter
e.g., 37 + 23 = 60 or (–37) + (–23) = – 60 (i) When a positive integer is added to an integer,
Rule II: To add a positive and a negative integer, the resulting integer is greater than the given
first we find the difference between the integer.
two and give the sign of the integer which (ii) When a negative integer is added to an
has greater numerical value. integer, the resulting integer is smaller than
e.g., –46 + 20 = (–26) as integer with the given integer.
negative sign has greater numerical value. (iii) Numbers such as –7 and +7, +9 and –9 when
Or 46 + (–20) = 26 as integer with added to each other give the sum zero. They
positive sign has greater numerical value. are called additive inverse of each other.

Let’s Attempt

Example 1: Add the following integers:
(i) 22 + (– 8) (ii) (– 43) + (+ 45) (iii) (– 217) + (– 100)

Solution: (i) 22 + (–8) = + (22 – 8) = 14 (ii) (– 43) + (+ 45) = + (45 – 43) = 2

(iii) (– 217) + (–100) = – (217 + 100) = – 317