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### Course: Arithmetic (all content)>Unit 4

Lesson 2: Number opposites

# Negative symbol as opposite

Opposites in math involve flipping the sign of a number. A positive number's opposite is the same number but negative, and vice versa. The negative symbol represents the concept of "opposite." When multiple negative symbols are applied, each one flips the number across the number line, resulting in a positive or negative value.

## Want to join the conversation?

• how about in multiplication when -4 x 4 = ?

• I know this is 4 years after, but still.
Think about a number line. When you multiply negative numbers you go more to the left of the number line, where there are more negative numbers. Just like 4x4=16, -4x4=-16. If you multiply +4 by 4, then you're moving to the right of the number line. The same idea applies.
• At , Sal says that he will use this symbol # to represent "number". Where does this symbol come from and why does it represent "number"?
• bruh he says opposite so many times in the video
• well, that is what the video is about
(1 vote)
• If you guys don't want to watch the whole video at regular speed just turn it to 2x speed.
• I dont get numbers like-(-7)
• One way to think of a negative sign is just 'inverting' or flipping whatever comes after it. If there is no negative sign, the positive sign (+) is implicit (assumed).
This means that 1 negative sign flips the sign from + to -.
A second negative sign (like -(-7)) flips the first negative sign back to a +.
A third (like -(-(-7))) would flip the sign to - again.

So, an odd number of - signs (1, 3 etc.) gives you a negative number, while an even number of - signs (0, 2 etc) gives you a positive number.
• guys every body like or comment so we can get davinds face reveal
• Math if my worst enemy sadly
• so is spelling
• Who argrees that Khan Academy is better than IXL?
• me(i do ixl)
(1 vote)
• at he explains that -|-3| when done is positive 3 but shouldn't it be -3
• You are using the absolute value bars which you give the correct answer, but Sal is not talking about absolute value, he uses parentheses such as -(-3) which is two negatives in a row and the answer is positive.
• I don’t understand dis
• basically, all he's saying is ANYTHING negative IS the opposite of it