Understanding Intervals Across 0 KS2 Revision
What you need to know
Things to remember:
- Adding a positive number is like taking away the negative from the positive.
- If we are taking away a big number from a small number, swap them around and put a minus on the answer.
Intervals across 0 just means adding and subtracting so that the numbers swap between positive and negative.
We all know how to add, it is just counting up.
What is 1+4?
So here, we’re starting at 1 and counting up 4 times.
We do this in the same way when adding a positive number to a negative number.
What is -1+4?
We started at -1 and counted up 4 to get 3, so -1+4=3. But, we also know that 4-1=3. So, we can change the numbers and make it into a subtraction question!
How about if we take a big number away from a small number? What is 4-6?
So, 4-6=-2. It is important to notice that 6-4=2. But why is this important? Let’s put them together to see
If we swap the numbers we are subtracting, we can see that the answer goes from negative to positive. So, when subtracting a big number from a small number, we can swap them around and just put a negative on the answer!
What is 9-15?
Question 1: What is -5+8?
Question 2: What is 7-19?