# Multiplying positive and negative numbers | Pre-Algebra | Khan Academy

## 93 thoughts on “Multiplying positive and negative numbers | Pre-Algebra | Khan Academy”

1. uttamo7 says:

lol he goes from vector fields to multiplying positive and negative numbers. the contrast!

2. Original Name says:

Monetary*

3. henzenc says:

Stokes' theorem is easy but I don't have a clue what this is about.

I just watch because it is pure pleasure, of course I know this stuff.

5. Rangha Hathakama Goya says:

stfu

6. Danielle Roxborough says:

You're so helpful. I love you.

7. deathstar gaming says:

boreing

8. deathstar gaming says:

yhe school makes you watch it

9. Victoria Colston says:

10. kerry brown says:

very smart

11. Emely Espino says:

THANK YOUUUUUUUUUUUUUUU OMG FINALLY I REMEMBER GOD BLESS YOU MY NIGGA

12. Sukhman Singh says:

Hi.. Am.. I was just wondering that what, application b or program do you use to write with a black background

Hey thank you so much for this video great work. I had some thought on this and this is what i came up with:

Multiplication is the Mathematical Operation of repeated Addition or Subtraction of numbers to provide an equivalent single value.

The numbers being multiplied are called the 'Factors' and the result is called the 'Product'.
Factor x Factor = Product

Example 1: What is the product of 5 x 2 = ?

The example above uses a 'Positive Integer' for the first 'Factor' and it tells us what Mathematical Operation Symbol to use and how many grouped brackets we will need.

If the first factor is a 'Positive Integer' write the Addition Symbol and then the 5 Grouped brackets:
+ ( ) ( ) ( ) ( ) ( )

The second 'Factor' tells us what number to place in the grouped brackets.

write the number inside the grouped brackets: + (2) (2) (2) (2) (2)

Once this information has been completed, add up all the values to give the result for the 'Product'. which is 10.

Example 2: What is the product of -4 x 3 = ?

The example above uses a 'Negative Integer' for the first 'Factor' and it tells us what Mathematical Operation Symbol to use and how many grouped brackets we will need.

If the first factor is a 'Negative Integer' write the Subtraction Symbol and then the 4 Grouped brackets:
– ( ) ( ) ( ) ( ) ( )

The second 'Factor' tells us what number to place in the grouped brackets.

write the number inside the grouped brackets: – (3) (3) (3) (3)

Following the Rule for Subtraction turn the Mathematical operation into addition and substitue the Subtrahends the groups of numbers in this case to their opposites:

Write it out: + (-3) (-3) (-3) (-3)

Once this information has been completed, add up all the values to give the result for the 'Product'. which is -12.

Hope this helps as it tries to incorporate the rules of addition and sbtraction

14. praveen manickavel says:

What if there was pos neg pos

15. purr claws says:

thank you!

16. robbertou says:

nice good job with this site guys

17. Nicholas O'Brien says:

I don't believe two negatives cancel each other out and make a positive any more than I believe two positives cancel each other out and make a negative. Can you help me?  I think maths would be neater if  -1 multiplied by -2= -1/2 not -1/-2 nor 2.   As mathematical negativity is positivist omission not positively expansive, I believe multiplication and division should be 'reversed' for double negative equations.  -1/-2= -2 not -1/-2 nor -1/2.  The reason not to leave -1/-2 equalling itself is in  order to perform the function of the equation instead of not performing a mathematical act.   Moreover as the negative numbers are omissive the larger number becomes the denominator in negative multiplication and a numerator in negative division.  Until negative numbers are treated as opposite to the whole values of positive numbers, maths may not become efficient enough to construct quantum computing.  This is because the bits in the computer will not be applied sensibly to their non-predictability.  Perhaps you could organise a computer calculator along this rule? I am not a mathematician but as a Political Scientist that two negatives can generate a number on the positive side of the number line smacks of delusional nihilism.  Can you help me?

18. Monika says:

(0:44)
I lol'd pretty hard right here.
Thank you for your work Sal! Caught up in 4 months cause of your site! Keep on do'n you!
l=D

19. Nusaibah Shahid says:

thank you!!

20. Sarah Louie says:

YEAH NOW I CAN DO MY WORK CORRECTLY AND NOT GET A F- LIKE LAST TIME!!!!

21. cooper nerf says:

thank you so much

22. MattsNotBanned_ says:

fuckin' math class..

23. dachosenone says:

Thanks Khan Academy! I no longer have to pay attention in class, because this is much easier!!

24. sean.christophr says:

25. Firas - says:

So what do you do if you have more than 3 multiplying?

26. Key5o says:

27. Ender Gaming says:

2 x X2 + 2 x -5

a=2
b=2
c=-5
__________
x= -b + or – √b2 – 4ac
__________
2a

28. VloggingMark says:

Thanks a LOT!!!!!!!!!!!!!!!! You are the BEST in teaching math 😉

29. T Burton says:

what is a=9, b=-24 i got this in math class.

30. William Yang says:

Twenty one yeah

31. William Yang says:

Math is awesome

THANK U

33. Brendan Berney says:

When I say "Eat!" I am encouraging you to eat (positive)

But when I say "Do not eat!" I am saying the opposite (negative).

Now if I say "Do NOT not eat!", I am saying I don't want you to starve, so I am back to saying "Eat!" (positive).

34. -Soca Bwoy- says:

OML finally i found a vid that can help me in math class!!!

35. Oblivion says:

who is watching this in 2016?

36. Oblivion says:

this helped a lot

37. autisticmangos says:

Thx i had this for homework and i got confused

38. Nautica Lopez says:

FINALLY I UNDERSTAND!

39. _뿌까유밍 says:

Thank you!!!!! This video helped me soooooo much preparing my test!!!!!

40. Andrew Gorgoglione says:

Dis stoof Is ez

41. Banana Ashel says:

Thank you. I liked and subscribed

42. Banana Ashel says:

I am watching this in 2016. I am creating a maths club that only some people are invited to. And it's secret. I'm the smartest at maths apart from my teacher or teachers in practically all of grade 4 at my school.

43. Humble narrator says:

thanks bro

44. xo says:

very well explained – tysm <3

45. kaci says:

oh wow i have always had trouble with negatives even though i'm almost in highschool and this really helped so thanks !

46. Noah Hardie says:

I had this problem while studying for my half yearly. You earned a sub

47. WarDrone says:

what if (-10) x (-100) x (-99) x 103 x (-105)?

you are literally the best at this ever… every video you've made has helped me beyond belief. I got a years worth of work done in 3 days because of you.. thank you so much!!

49. Julier101 says:

Thanks so much! you helped me figure out how to do it

50. Eduardo Acevedo Martinez says:

how come u guys explain better than the real teachers

51. EKB 1130 says:

Y u make it good but still so less watch?

52. Wang Fai Chiu says:

He said-2 into -6 that is funny

53. Fredthegamer SCHRARDER says:

thanks this helped

54. Andrea savic says:

Jokes aside, this actually helped me. thxxxx

55. _EllieJoe _ says:

He helps me so much I’ve gone to this channel b4 and he’s great at explaining cuz my math teacher isn’t so I go to him

56. Jessica21Jones says:

This is what I needed. I learn best through example, not by pictures or words.

57. 優Swish says:

Gee thanks man!!!

58. SHEIKH IHMID says:

shukran

59. iMystique says:

thank you so much! you just saved me from failing my negative numbers exam lol.

60. Diana D.D says:

I have a login in khan academy my name is Diana112233 it was kinda hard to find a good name lol

61. Diana D.D says:

Thanks so much

62. marley casey says:

coo

63. SG - 09ZT - Humberview SS (2472) says:

on ixl it says this is wrong :/

64. Cortez Anderson says:

thank you

65. Pumpkin Kitty says:

they made us watch this in school and i already knew dis :')

66. Darcy Sanderson says:

i dont get this to old style

67. iEvxl says:

Thank u

68. Ping King says:

Is there a possibility of a negative five having its own square root?

69. Emily Kirstein says:

I get it now

70. bubbys stay bubbys says:

71. KK Unknown says:

My math teacher sucks when it comes to her teaching us… BUT THIS VID… HELPS SO MUCH. THANK U! 🤗

72. Henry Rossetti ( Student ) says:

get off ms pait

73. MTB&more says:

Go watch the video ur gonna fail the test u have tomorrow lmao

74. Tan TDX says:

this helped a lot thanks

math sux

76. Nikolai Evans says:

OH MY GOD THE DISLIKE BUTTON WORKS THE DISLIKE BUTTON RELLEY WORKS!!!!! :))))_

77. Dejoy 1066 says:

Thx youre voice is chill

78. Sâváge Eva says:

Thanks for this

79. vWolvez says:

who else came here from seneca learning

80. ItsChips InGames says:

What I do is I Just Imagine The Odd And Even In Addition (I’m That 22Jtran Dude U Gave The Coding award to)

81. Francis dcruz says:

U r so good at explaining……. Thankx a lot

82. Officer chief john says:

i came here from khan acadamy.org

83. Alliee X says:

Thank you so much

84. RANDOMS says:

I’m not not tired

I’m tired

85. RANDOMS says:

You are jesus

86. 10000 Subscribers With No Video Challenge says:

hi

87. android pc tips tricks and much more says:

Thanks a lot

88. Hi Ok says:

what about multiple positive and negatives? such as: (-5) x 6 x (7) how do you know what sign to use? please help!

89. Julia Berezowski says:

I really like khan Academy because they explain so clearly then the teachers in my school!

90. Master Jabz says:

Lol my last name is khan and everyone in class was looking at me when the teacher was showing them

91. Abdurahman Bello says:

Thanks

92. day6kilogram says:

i supposed to open youtube 7 years ago

93. Jose Ferrero says:

True