why does it say subtract when you have to add

Because two negatives equal a positive in a subtraction when it's next to each other. 3-(-6)=9=3+6=9

Negative minus a positive is a negative?

Yes, subtracting a positive always makes the number smaller.

So basically 2 negatives make a positive?

You could be mistaking this for a multiplication problem. negative * negative = positive but in addition negative + negative = negative.

I am confused that 8 - (-2) means you add up. IS that count Mr.Khan?

Because when you do a subtraction problem with a positive taken away, you go down. 8 - 2 = 6 When that's negative, you have the _opposite_, so you go up. 8 - ( - 2 ) = 10 You still might wonder why it isn't - 10, but I can answer it. Subtraction and addition like this stuff are never gonna give you negative.

why does it add when it says to subtract?

When you have a double negative, or two negatives in a row, it is the same as having a positive. 2+2 = 2-(-2) there are two negatives in a row so it becomes positive.

Is there an easier way to solve these without wasting space on a worksheet of paper?

Just change the sign of the second number and add

I don't get why they are swiching the signs telling me to add when I have to subtract. I just don't understand at all.

Another way to think of a negative sign is as an OPPOSITE sign. So when you are subtracting a negative, it's really telling you to do the opposite of subtracting, which ends up being adding. Another way some people might look at it is to think of someone telling you that you no longer owe them any money you borrowed. By taking away your debt (subtracting a negative), they have given you a gift (adding a positive).

wait so a negative minus a negative is the same as a positive plus a positive?

you almost got it a negative plus a positve is a negative so say i have -9 dollars and i borrow some from the bank wich is 10 dollars so now i owe the bank 10 dollars so now i have -90 dollars hope this helps

so two negatives make a positive

It depends on the operation. Adding two negatives always makes a negative. Subtracting two negatives could make zero, a negative, or a positive depending on how the two negatives compare to each other. Multiplying or dividing two negatives always makes a positive.

Main content

7th grade (Illustrative Mathematics)

Course: 7th grade (Illustrative Mathematics) > Unit 5

Lesson 5: Lesson 5: Representing subtraction

Subtracting negative numbers review

CCSS.Math:

7.NS.A.1

7.NS.A.1c

Google Classroom

Review the basic of subtracting negative numbers and try some practice problems.

Subtracting negative numbers

Subtracting a number is the same as adding the opposite of the number.

Let's look at two examples:

minus, 5, start color #e07d10, minus, 7, end color #e07d10, equals, minus, 5, start color #e07d10, plus, left parenthesis, minus, 7, right parenthesis, end color #e07d10

10, start color #e07d10, minus, left parenthesis, minus, 3, right parenthesis, end color #e07d10, equals, 10, start color #e07d10, plus, 3, end color #e07d10

Note: In both examples, we change subtraction to addition and changed the sign of the second number to the opposite sign.

Want to know why this works? Check out this video.

Once we have an addition problem, we can solve.

Example 1: negative minus negative

Lets subtract minus, 5, minus, left parenthesis, minus, 6, right parenthesis.

Step 1: Rewrite as an addition problem

minus, 5, start color #e07d10, minus, left parenthesis, minus, 6, right parenthesis, end color #e07d10, equals, minus, 5, start color #e07d10, plus, 6, end color #e07d10

Step 2: Start at the first number in the addition problem, in this case minus, 5:

Step 3: Move 6 places to the right. We move 6 to the right because adding positive 6 increases our number by 6.

minus, 5, plus, 6 takes us to 1 on the number line.

minus, 5, minus, left parenthesis, minus, 6, right parenthesis, equals, 1

Example 2: negative minus positive

Lets subtract minus, 4, minus, 7.

Step 1: Rewrite as an addition problem

minus, 4, start color #e07d10, minus, 7, end color #e07d10, equals, minus, 4, start color #e07d10, plus, left parenthesis, minus, 7, right parenthesis, end color #e07d10

Step 2: Start at the first number in the addition problem, in this case minus, 4:

Step 3: Move 7 places to the left. We move 7 to the left because adding negative 7 decreases our number by 7.

minus, 4, plus, left parenthesis, minus, 7, right parenthesis takes us to minus, 11 on the number line.

minus, 4, minus, 7, equals, minus, 11

Want to learn more about subtracting negative numbers? Check out this video.

Practice

Problem 1

Current

Subtract.

minus, 8, minus, left parenthesis, minus, 2, right parenthesis, equals

Want to try some more subtracting negative numbers problems? Check out this exercise.

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hesasoccerplayer
Posted 6 years ago. Direct link to hesasoccerplayer's post “why does it say subtract ...”
why does it say subtract when you have to add
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(253 votes)
Answer
- Goldstein
  Posted 4 years ago. Direct link to Goldstein's post “Because two negatives equ...”
  Because two negatives equal a positive in a subtraction when it's next to each other. 3-(-6)=9=3+6=9
  Comment on Goldstein's post “Because two negatives equ...”
  (105 votes)
mysticeye8206
Posted 5 years ago. Direct link to mysticeye8206's post “Negative minus a positive...”
Negative minus a positive is a negative?
Button navigates to signup pageComment on mysticeye8206's post “Negative minus a positive...”
(70 votes)
Answer
- Nicholas
  Posted 5 years ago. Direct link to Nicholas's post “Yes, subtracting a positi...”
  Yes, subtracting a positive always makes the number smaller.
  Comment on Nicholas's post “Yes, subtracting a positi...”
  (51 votes)
Drew Creeger
Posted 5 years ago. Direct link to Drew Creeger's post “So basically 2 negatives ...”
So basically 2 negatives make a positive?
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(55 votes)
Answer
- Xiran Bo
  Posted 2 years ago. Direct link to Xiran Bo's post “You could be mistaking th...”
  You could be mistaking this for a multiplication problem. negative * negative = positive but in addition negative + negative = negative.
  Comment on Xiran Bo's post “You could be mistaking th...”
  (8 votes)
Nasir
Posted 4 years ago. Direct link to Nasir's post “So, correct me anyone if ...”
So, correct me anyone if I'm wrong. So let's say I have
-4-(-4), wouldn't equal 0? Because instead of me subrtracting with -4, I have to add it. So, would it be 0 instead of -8?
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- Gracie
  Posted 10 months ago. Direct link to Gracie's post “Yes that is correct.”
  Yes that is correct.
  Comment on Gracie's post “Yes that is correct.”
  (8 votes)
Ton, Quan
Posted 3 years ago. Direct link to Ton, Quan's post “I am confused that 8 - (-...”
I am confused that 8 - (-2) means you add up. IS that count Mr.Khan?
Button navigates to signup pageComment on Ton, Quan's post “I am confused that 8 - (-...”
(16 votes)
Answer
- summerdean66
  Posted 3 years ago. Direct link to summerdean66's post “Because when you do a sub...”
  Because when you do a subtraction problem with a positive taken away, you go down. 8 - 2 = 6 When that's negative, you have the opposite, so you go up. 8 - ( - 2 ) = 10 You still might wonder why it isn't - 10, but I can answer it. Subtraction and addition like this stuff are never gonna give you negative.
  Comment on summerdean66's post “Because when you do a sub...”
  (11 votes)
fjones
Posted 4 years ago. Direct link to fjones's post “why does it add when it s...”
why does it add when it says to subtract?
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(14 votes)
Answer
- Madeleine
  Posted 4 years ago. Direct link to Madeleine's post “When you have a double ne...”
  When you have a double negative, or two negatives in a row, it is the same as having a positive.
  2+2 = 2-(-2) there are two negatives in a row so it becomes positive.
  Comment on Madeleine's post “When you have a double ne...”
  (11 votes)
emma.durrett
Posted 4 years ago. Direct link to emma.durrett's post “I don't get why they are ...”
I don't get why they are swiching the signs telling me to add when I have to subtract. I just don't understand at all.
Button navigates to signup pageComment on emma.durrett's post “I don't get why they are ...”
(8 votes)
Answer
- jbraddock
  Posted 4 years ago. Direct link to jbraddock's post “Another way to think of a...”
  Another way to think of a negative sign is as an OPPOSITE sign. So when you are subtracting a negative, it's really telling you to do the opposite of subtracting, which ends up being adding.
  Another way some people might look at it is to think of someone telling you that you no longer owe them any money you borrowed. By taking away your debt (subtracting a negative), they have given you a gift (adding a positive).
  Comment on jbraddock's post “Another way to think of a...”
  (25 votes)
Shelby
Posted 3 years ago. Direct link to Shelby's post “so two negatives make a p...”
so two negatives make a positive
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(5 votes)
Answer
- Ian Pulizzotto
  Posted 3 years ago. Direct link to Ian Pulizzotto's post “It depends on the operati...”
  It depends on the operation.
  Adding two negatives always makes a negative.
  Subtracting two negatives could make zero, a negative, or a positive depending on how the two negatives compare to each other.
  Multiplying or dividing two negatives always makes a positive.
  Button navigates to signup page
  (5 votes)
lluster
Posted 5 years ago. Direct link to lluster's post “Is there an easier way to...”
Is there an easier way to solve these without wasting space on a worksheet of paper?
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(13 votes)
Answer
- zaleigh.latham
  Posted 2 years ago. Direct link to zaleigh.latham's post “Just change the sign of t...”
  Just change the sign of the second number and add
  Comment on zaleigh.latham's post “Just change the sign of t...”
  (11 votes)
Olivia O
Posted 3 years ago. Direct link to Olivia O's post “wait so a negative minus ...”
wait so a negative minus a negative is the same as a positive plus a positive?
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(6 votes)
Answer
- David
  Posted 2 years ago. Direct link to David's post “you almost got it a negat...”
  you almost got it a negative plus a positve is a negative so say i have -9 dollars and i borrow some from the bank wich is 10 dollars so now i owe the bank 10 dollars so now i have -90 dollars hope this helps
  Comment on David's post “you almost got it a negat...”
  (11 votes)