Negative numbers
We are used to dealing with numbers by now and here we introduce negative
numbers.
Can you remember the proper name for whole numbers?
Integers
So today we are going to look at negative
integers.
If we have a number line we can put any number on it.
Here is a number line. Guess which numbers go in the positions A, B, C.
| Answer | A = 2 B = 6 C= 7 |
We can easily see that each number is spaced equally along the number line and the more we go to the right the bigger the numbers get.
What happens if we move to the left?
That's right, the numbers get smaller.
Look at this number line. Guess which numbers go in position A, B, C,
Here we can see that as we mover more to the left the numbers get smaller. But they follow them same pattern; on the right of zero they increase each time by one, so on the left of zero they decrease by one
Here is a question for you.
Using the number line, find out how many spaces there are between the number 1 and the letter B.
B = -3 so this is the difference between 1 and -3
Remember that difference means subtract or take away!
That wasn't hard was it?
Here is another number line and some questions based on it.
What is the difference between the following numbers.
(a) 1 and 3
(b) -2 and 0
(c) -4 and 2
(a) The difference between 1 and 3 is 2
(b) The difference between -2 and 0 is 2
(c) The difference between -4 and 2 is 6
Try these last few as an introduction to negative integers
1. What do I have to subtract from 3 to get to 0?
2. What to I have to add to -1 to get to 0?
3. What does 2 -4 =?
4. What do I have to add to -2 to get to 4?
Here are the answers. If you got any wrong go back to the question and look at the number and see how we got the answer.
| 1. What do I have to subtract from 3 to get to 0? | 3 |
| 2. What to I have to add to -1 to get to 0? | 1 |
| 3. What does 2 -4 =? | -2 |
| 4. What do I have to add to -2 to get to 4? | 6 |
Number lines can go up and down too. Here is a SATs type question to finish off with.
By how many degrees had the temperature increased between the two readings during the day?
Answer
The temperature at 8 am was -3 degrees. The temperature at 2 pm was 4 degrees so the difference was 7 degrees.
That is a typical SAT question on negative integers. I hope you feel happier with those nasty negatives now!
Good luck!