Apply addition and subtraction rules

Key notes:

1. Addition of Integers:

  • Same Signs: Add the absolute values (ignore the signs), then give the sum the same sign as the numbers.
    • Example: 5 + 3= 8 or −5+(−3)=−8
  • Different Signs: Subtract the smaller absolute value from the larger absolute value, and then assign the sign of the number with the larger absolute value.
    • Example: 5+(−3)= 2 or −5+3=−2

2. Subtraction of Integers:

  • Change to Addition: To subtract a number, add its opposite.
    • Example: 7 − 5 = 7 + (−5) = 2
    • Example: −7 − 5 = −7 + (−5) = −12
  • Same Signs: When subtracting numbers with the same sign, subtract the absolute values and then keep the sign.
    • Example: −8 −(−3) = −8 + 3 = −5

Learn with an example

💡 The number line shows an unknown number, w.

💡 Is w positive or negative?

  • positive
  • negative
  • The unknown number w is to the right of 0. So, w is positive.

💡 The number line shows an unknown number, p.

💡 Is p positive or negative?

  • positive
  • negative
  • The unknown number p is to the left of 0. So, p is negative.

💡 The number line shows an unknown number, q.

💡 Is q positive or negative?

  • positive
  • negative
  • The unknown number q is to the left of 0. So, q is negative.

Let’s practice! 🖊️