Page 47 - ICSE Math 6

Example 14: In the figure given alongside, fill in the boxes with integers
such that the sum of the integers in two boxes is equal to
the integer in the box directly above them.
4
Solution: –7 8 3 –12

3 –10
4 –1 –9
8 –4 3 –12

Points to remember

• When a positive integer is added to a given integer, the resulting integer becomes greater than the
given integer.
• When a negative integer is added to a given integer, the resulting integer becomes less than the
given integer.

Addition of integers on a number line
To add a positive integer, say a, to a given integer on the number line, we move a units to the right
of the given integer on the number line. For example, to add +3 to +5, we move 3 units to the right
of 5 on the number line.

–1 0 1 2 3 4 5 6 7 8
\ (+5) + (+3) = +8

To add a negative integer, say –b, to a given integer on the number line, we move b units to the left
of the given integer on the number line. For example, to add –3 to –5, we move 3 units to the left of
–5 on the number line.

–8 –7 –6 –5 –4 –3 –2 –1 0 1

\ (–5) + (–3) = –8
Example 15: Add +6, –4 and –8 on the number line.

Solution: Move 6 units to the right of 0 to reach 6 and then move Try These
4 units to the left of 6 to reach 2. Finally, move 8 units
to the left of 2 to reach –6. 1. Add (+6) and (–3) on the
number line.
2. Find the value of (–2) + (+4)
using the number line.
3. Is it correct to say that one
–6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 should move 5 units to the
\ (+6) + (–4) + (–8) = –6 left of –4 on the number line
to find (–4) + (+5)?
Subtraction of integers
Subtracting a positive integer is the same as subtracting its absolute value, and subtracting a negative
integer is the same as adding its absolute value.

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