Addition of Numbers without using Number Line

Learn the rules used for addition of numbers without using number line. When the numbers are big, the use of number line is not convenient for their addition. Also, it is very time consuming to draw a number line every time, and perform the operation of addition.

Rules for addition of numbers without using number line in different situation:

1. To add a positive (+ ve) number to a positive (+ ve) number, the numbers should be added and positive sign should be attached to the sum obtained.

For example:

(i) Evaluate (+4) + (+3) = 4 + 3 = 7 or +7.

(ii) Evaluate (+5) + (+4) = 5 + 4 = 9 or +9.

2. To add a positive number to a negative number, the numbers with smaller value should be subtracted from the number with bigger value and the sign of the bigger number should be attached to the answer.

For example:

(i) Evaluate (+5) + (-2)

On subtracting smaller number 2 from bigger number 5; we get 5 – 2 = 3

Since, the sign of bigger number is + (positive)

Therefore, (+5) + (-2) = +3 or simply 3

(ii) Evaluate (+6) + (-1)

On subtracting smaller number 1 from bigger number 6; we get 6 – 1 = 5

Since, the sign of bigger number is + (positive)

Therefore, (+6) + (-1) = +5 or simply 5

3. To add a negative number to a positive number, the numbers with smaller value should be subtracted from the number with bigger value and the sign of the bigger number should be attached to the answer.

For example:

(i) Evaluate (-4) + (+1)

On subtracting smaller number 1 from bigger number 4; we get 4 – 1 = 3

As the sign of bigger number is negative (-)

Therefore, (-4) + (+1) = -3

(ii) Evaluate (-8) + (+3)

On subtracting smaller number 3 from bigger number 8; we get 8 – 3 = 5

As the sign of bigger number is negative (-)

Therefore, (-8) + (+3) = -5

4. To add a negative number to a negative number, the numbers should be added and negative sign should be attached to the sum obtained.

For example:

(i) Evaluate (-4) + (-1) = -5