Addition and Subtraction:

What Does it Mean to Subtract a Negative Number?

Subtracting a negative number is the same as adding a positive number.

Example: \(-5- (-2)=-3\)

This is a number line centered at the number negative 5. A blue dot is on the number negative 5. A blue arrow line starts to point left from the negative 5, but then curves around to point right. Another blue line bounces from negative 5, to the right, landing first on negative 4 and then stopping on negative 3. A red dot is on the number negative 3 and a note says, “End at negative 3.”

Video Source (03:34 mins) | Transcript

Additional Resources

Khan Academy: Subtracting a Negative

Practice Problems

Evaluate the following expression:

\(6-(- 3)=?\)
\(4-(- 4)=?\)
\(3-(- 5)=?\)
\(4-(- 8)=?\)
\(10-(- 19)=?\)
\(48-(- 16)=?\)

Solutions

9 (Written Solution)

Let’s explore the patterns:

\(6-(1)=5\)

\(6-(0)=6\)

\(6-(-1)=7\)

\(6-(-2)=8\)

\({\color{Red} 6-(-3)=9}\)

Subtracting a negative number from a positive number result in a positive answer. This problem can also be re-written as 6 + 3 = 9.
8 (Written Solution)

Let’s explore the patterns:

\(4-(1)=3\)

\(4-(0)=4\)

\(4-(-1)=5\)

\(4-(-2)=6\)

\(4-(-3)=7\)

\({\color{Red} 4-(-4)=8}\)

Subtracting a negative number from a positive number results in a positive answer. This problem can also be re-written as 4 + 4 = 8.
8 (Solution Video | Transcript)
12 (Solution Video | Transcript)
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