1. How to add/subtract positive and negative numbers

2. Adding Rules: Positive + positive= positive Negative+negative= negative E.g. 8+7= (positive) 15 -5+-6= (negative) -11 However if it were to be positive and minus the answer would be either + or - : (depending on the question) E.g. -8+5= (negative) -3 -5+8= (positive) 3

3. Subtracting Rules: Positive - positive = negative or positive Negative - negative = positive E.g. 3-7= (positive) 5 5-6= (negative) -1 -5--2= (positive) 7 However when subtracting + and - numbers the answer is negative: E.g. -5-7= (negative) -12

4. Using a number line Use a number line when adding and subtracting to make it easier. Try these questions using the number line. Check your answers on the next slide 1. -5+-7= 2. 5-8= 3. -9--7= 4. 10+8= 5. -2-8= 6. 9-3= 7. -9+7=

5. Answers 1. -12 2. -3 3. 16 4. 18 5. -10 6. 6 7. -2 By Sara Tattley