Multiplying Negative Numbers

This video demonstrates multiplication with integers using a number line and representing multiplication as repeated addition. It is revealed that calculating the opposite (Additive Inverse) of a number is accomplished by multiplying the number by negative one. It should be mentioned to students that calculators have an opposite key labeled as (-) or (+/-) where pressing this key multiplies the quantity on the screen by negative one to calculate its opposite. The fact that "the opposite of a negative number is always positive" is used to explain the reasoning behind why a "negative times a negative" must be positive.

[@earthygreen]

This video helped a *GREAT* deal. However, near the end, shouldn't the multiplied equations be worked from left to right, not from right to left?

[@dayanara.]

Thanks this video helped alot

[@htainlindwa9961]

I thought when you read 2 time 3 it means 3 added two time .

[@akashkaushik1]

Can you show (5*-1) instead of (-1*5), I think you will need another axis to show that.

[@muchomath]

5*-1 would be shown exactly as -1*5 because of the commutative property for multiplication. 3*2 = 2*3 and therefore 5*-1= -1*5. It's all about the patterns that occur in math. Therefore I used the commutative property to demonstrate 5*-1 as -1*5. That's the best answer I can give. Thanks for stopping by :) Professor Perez

[@alittax]

Here's another explanation: czcams.com/video/eV6iYvd4KS0/video.html&ab_channel=DrJamesTanton

[@youngknowledgeseeker]

​@@muchomath NO, our problem is that its EASY to visualize (-1) 5 times. -1-1-1-1-1=5. So easy.
It's NOT easy to conceptualize 5 (-1) times. 5-5=0.
What are we missing here????

[@nibeditasamal8993]

This is the most in helping vidio

[@jnyfknblz]

please show negative times negative on a number line.

[@muchomath]

Well, demonstrating a negative times a negative on a number line would look exactly the same as showing the multiplication of two positive numbers on the number line. It's tough to explain that -2*-5 is the same as 2*5. All I can say that math is all about patterns and two negatives multiplied together giving a positive result fits into the pattern. But I personally stick to the understanding that opposites of negative numbers are always positive as I demonstrated in the video. I wish there was an easier way to explain this, but that's the best I can do. Thanks for stopping by. I hope you find these videos useful :) Professor Perez

[@mennamanaminoo5054]

@@muchomath
You can make Equation like that :
0 = 5- * ( 2 + 2- )
0 = 5-* 2 + 5- * 2-
0 = (10-) + ( ...... )
So the answer will be -2 * -5 = 10
Because 10 -10 = 0

[@alittax]

Here's another explanation: czcams.com/video/eV6iYvd4KS0/video.html&ab_channel=DrJamesTanton

[@llee2096]

He did. Keep this because you will never find a better explanation.

[@alittax]

@@llee2096
This might be one:
czcams.com/video/eV6iYvd4KS0/video.html&ab_channel=DrJamesTanton

[@Kingboigamer]

- x - is positive. How would you show it on a number line. The most important point just like today's teachers was skipped.

[@marinawilkinson5840]

Confusing. Too fast.

[@jordyndavidson3825]

You can go to settings and change the playing speed

[@anguspollerd442]

thx

[@frui7cake150]

Hi I'm joe

[@TariqKhan-bw9py]

Another failure!

[@bittubittu6078]

Sir what your comment meant