Page 93 - Maths Class 06

Addition of Integers
On a number line, + 4 represents a movement of 4 units to the right of zero and – 4 represents a
movement of 4 units to the left.
Let us now try to represent ‘4 + 5’ on the number line. We begin from 0 and move 4 units to the right. We
each 4. From here, we further move 5 units to the right and reach 9.

–4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9

Let us now represent – 4 + 6 on the number line. We first move 4 units to the left of zero and then from
there, 6 units to the right to account for + 6. We will finally reach 2.

–5 –4 –3 –2 –1 0 1 2 3 4 5

Thus, – 4 + 6 = 2
Now, let us represent (– 3) + (– 4) on the number line. We first move 3 units to the left of zero to account
for – 3 and further move 4 units to the left again to account for – 4. Thus we reach – 7.

–8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3

Thus, (-3 ) (+ -4 ) = -7

EXAMPLE 1. Add +3 and -8 on the number line.
SOLUTION : We start from 0 and move 3 steps to the right to reach A. Now starting from A, we move 8
steps to the left to reach B, as shown below:

B A
–6 –5 –4 –3 –2 –1 0 1 2 3 4

Clearly B represents the integer -5.

\ 3 + -( 8 =) 5
EXAMPLE 2. Add -3 and -6 on the number line.

SOLUTION : We start from 0 and move 3 steps to the left to reach A. Now starting from A, we move 6
steps to the left to reach B, as shown below:

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

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