Rules to Add Integers
Rule 1:
When the two integers have the positive sign, add the integers and assign the (+) sign to the sum.
Combination One:
(positive + positive) or (+ plus +)
For example:
Find the sum of the integers.
(i) 8 + 19 = 27
(ii) 33 + 25 = 58
(iii) 42 + 91 = 133
(iv) 59 + 87 = 146
Note:
Here, we have two integers having the same (+) sign. So, we add the numbers and attach (+) sign to the sum.
Rule 2:
When the two integers have the negative sign, add the integers and assign the (-) sign to the sum.
Combination Two:
(negative + negative) or (– plus –)
For example:
Find the sum of the integers.
(i) (-7) + (-9) = -16
(ii) (-23) + (-15) = -38
(iii) (-41) + (-57) = -98
(iv) (-119) + (-137) = -256
Note:
Here, both the integers have the same (-) sign. So, we add the numbers and attach the (-) sign to the sum.
Rule 3:
When the two integers have opposite sign [one positive (+) and other negative (-)], find the difference of the numbers and to the difference assign the sign of the integer having greater value.
1. Combination Three:
(negative + positive) or (– plus +)
For example:
Find the sum of the integers.
(i) (-17) + 29
= -17 + 29
[Here, two integers are with unlike signs – and +.We find the difference of the numbers is 12 and to the difference attach the sign of the integer having greater value; so the answer is positive 12].
= 12
(ii) (-81) + (+35)
= -81 + 35
[Here, two integers are with unlike signs – and +.We find the difference of the numbers is 46 and to the difference attach the sign of the integer having greater value; so the answer is negative 46].
= -46
2. Combination Four:
(positive + negative) or (+ plus –)
For example:
Find the sum of the integers.
(i) (+79) + (-57)
= 79 – 57
[Here, two integers are with unlike signs + and -.We find the difference of the numbers is 22 and to the difference attach the sign of the integer having greater value; so the answer is positive 22].
= 22
(ii) (+85) + (-121)
= 85 – 121
[Here, two integers are with unlike signs + and -.We find the difference of the numbers is 36 and to the difference attach the sign of the integer having greater value; so the answer is negative 36].
= -36
In adding integers these are the possible rules to add integers.