Page 122 - ICSE Math 5

Example 15: Subtract 4 from 3.
Solution: 3 – 4 = ? (Here, the subtrahend = 3 and the minuend = 4.)
Move 3 steps to the right of 0 to reach 3.

Since the minuend is a positive integer, start from 3 and move 4 steps to the left.

–10 –9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9 10
So, (+3) – (+4) = 3 – 4 = –1.
Note: When there is a negative sign outside the bracket and a positive sign inside
the bracket, the sign changes to negative.

Subtraction of a positive integer from a negative integer

When the subtrahend is a negative integer and the minuend is a positive integer, first move to
the left of 0 to reach the subtrahend and then again to the left of the subtrahend to find the
difference.

Example 16: Subtract 4 from (–3).
Solution: (–3) – (+4) = ? (Here, the subtrahend = –3 and the minuend = 4.)
Move 3 steps to the left of 0 to reach –3. Since the minuend is a positive integer,
start from –3 and move 4 steps further to the left of –3 to reach –7.

–10 –9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9 10
So, (–3) – (+4) = –3 – 4 = –7.

Subtraction of a negative integer from a positive integer

When the subtrahend is a positive integer and the minuend is a negative integer, first move to the
right of 0 to reach the subtrahend and then to the right of the subtrahend to find the difference.

Example 17: Subtract (–8) from 4.
Solution: (+4) – (–8) = ? (Here, the subtrahend = 4 and the minuend = –8.)

Move 4 steps to the right of 0 to reach 4. Since the minuend is a negative integer,
start from (+4) and move 8 steps further to the right of 4 to reach 12.

–10 –9 –8 –7 –6 –5 –4 –3 –2 –1 0 1 2 3 4 5 6 7 8 9 10 11 12
So, 4 – (–8) = 4 + 8 = 12.

Note: When there is a negative sign outside the bracket and also a negative sign
inside the bracket, the sign changes to positive.

Subtraction of a negative integer from a negative integer

When both the subtrahend and the minuend are negative integers, first move to the left of 0 to
reach the subtrahend and then move to the right of the subtrahend to find the difference.

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