Adding negative whole numbers

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

Number line spanning minus 8 to plus 8.

When you add a positive number, go up the number line.

When you subtract a positive number, go down the number line.

Example 1

\[6 - 3 = 6 + (\,- \,3) = 3\]

Number line spanning 3 to 6.

Example 2

\[4 - 5 = 4 + (\,-\,5) = - 1\]

Number line spanning minus 1 to plus 4

Example 3

\[ -\,2 + 5 = 3\]

Number line spanning minus 2 to plus 3

Now try these questions and remember the number line!

Question

\[4 - 9\]

\[4 - 9 = 4 + (\,-\,9) = -\,5\]

Number line spanning minus 5 to plus 4
Question

\[3 - 10\]

\[3 - 10 = 3 + (\,-\,10) = -\,7\]

Number line spanning minus 7 to plus 3
Question

\[- 9 + 12\]

\[- 9 + 12 = 3\]

Number line spanning minus 9 to plus 3