Introduction

In this lesson, you will learn how to subtract negative numbers. Subtracting a negative number is the same as adding a positive number.

This video illustrates the material from the lesson below. Watching the video is optional.

• Subtracting a Negative Number (03:34 minutes) | Transcript

Subtraction of a Negative Number

What Does It Mean to Subtract a Negative Number?

Example 1

\(1 - -3\)

First, you need to understand that 1−−3 1 - -3 1−−3 is the same as 1−(−3) 1 - (-3) 1−(−3). If you use a number line to demonstrate the answer, you start at 1. Move to the left because of the subtraction sign, but then go in the opposite direction (to the right) because of the negative in front of the 3 (see Figure 1).

Figure 1

Once again, this example demonstrates that two negatives next to each other make a positive. −(−3) -(-3) −(−3) becomes +3 +3 +3: So 1−(−3)=4 1 - (-3) = 4 1−(−3)=4 is the same as 1+3=4 1 + 3 = 4 1+3=4.

Figure 2

Example 2 \(-5-(-2)\)

On a number line, start at -5. The subtraction sign directs you to the left, but the negative sign in front of the number 2 redirects you in the opposite direction. So, you will move 2 units to the right (see Figure 3).

Figure 3

\(-5 - (-2)\) is the same as \(-5 + 2\), so both give the same answer: -3.

This shows that subtracting a negative number is the same as adding a positive number.

Remember

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

Practice Problems

1. \(6 - (- 3) = ?\) (
   Solution

   x

   Solução: 9
   Detalhes:
   Explore os padrões:
   
   \(6 - (1) = 5\)
   
   \(6 - (0) = 6\)
   
   \(6 - (-1) = 7\)
   
   \(6 - (-2) = 8\)
   
   \(\color{red} 6 - (-3) = 9\)
   
   Subtrair um número negativo de um número positivo resulta em uma resposta positiva. Este problema também pode ser reescrito como \(6 + 3 = 9\).
   )
2. \(4 - (- 4) = ?\) (
   Solution

   x

   Solução: 8
   Detalhes:
   Explore os padrões:
   
   \(4 - (1) = 3\)
   
   \(4 - (0) = 4\)
   
   \(4 - (-1) = 5\)
   
   \(4 - (-2) = 6\)
   
   \(4 - (-3) = 7\)
   
   \(\color{red} 4 - (-4) = 8\)
   
   Subtrair um número negativo de um número positivo resulta em uma resposta positiva. Este problema também pode ser reescrito como \(4 + 4 = 8\).
   )
3. \(3 - (- 5) = ?\) (
   Solution Video

   x

   Solução: 8
   Detalhes:
   
   | Transcript)
4. \(4 - (- 8) = ?\) (
   Solution Vídeo

   x

   Solução: 12
   Detalhes:
   
   | Transcript)
5. \(10 - (- 19) = ?\) (
   Solution

   x

   Solução: 29
   )
6. \(48 - (- 16) = ?\) (
   Solution

   x

   Solução: 64
   )