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Home > Maths I > Numbers and Money > Negative whole numbers

Maths I

Negative whole numbers

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Adding negative whole numbers

You might find a number line useful when answering questions involving negative numbers.

Horizontal numberline counting from minus 8 to plus 8, through all the intergers.
  • When you add a positive number, go up the number line.
  • When you subtract a positive number, go down the number line.

Example 1

  • 6 - 3
  • = 6 + (- 3)
  • = 3
  • Numberline from 3 to 6, left to right. At the right side, it says start here and an arrow points backwards from 6 to 3.

Example 2

  • 4 - 5
  • = 4 + (- 5)
  • = - 1
  • Numberline going from minus 1 to 4, left to right. Says start here at the right side with an arrow pointing backwards from 4 to minus 1.

Example 3

  • - 2 + 5
  • = 3
  • Numberline from minus 2 to plus 3. At the left it says start here and an arrow points from left to right, from minus 2 to 3.

Now try these questions:

Remember the number line!

Question

4 - 9

Answer
  • 4 - 9
  • = 4 + (- 9)
  • = - 5
  • Horizontal line with minus 5 at the left end, and plus 4 at the right end. There are no numbers in between. An arrow points from the 4 to the minus 5.
Question

3 - 10

Answer
  • 3 - 10
  • = 3 + (- 10)
  • = - 7
  • Horizontal line with minus 7 at the left end and plus 3 at the right end. There are no numbers in between. An arrow points from the 3 to the minus 7.
Question

- 9 + 12

Answer
  • - 9 + 12
  • = 3
  • Horizontal line with minus 9 at the left end and plus 3 at the right end. There are no numbers in between. An arrow points from minus 9 to 3.

If you got these correct, well done.

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