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Converting decimals to fractions example 1 | Decimals | Pre-Algebra | Khan Academy

Converting decimals to fractions example 1 | Decimals | Pre-Algebra | Khan Academy


Let’s see if we can
write 0.15 as a fraction. So the important
thing here is to look at what place these
digits are in. So this 1 right over here,
this is in the tenths place, so you could view
that as 1 times 1/10. This 5 right over here is
in the hundredths place, so you could view
that as 5 times 1/100. So if I were to rewrite
this, I can rewrite this as the sum of– this 1
represents 1 times 1/10, so that would literally
be 1/10 plus– and this 5 represents
5 times 1/100, so it would be plus 5/100. And if we want to
add them up, we want to find a
common denominator. The common denominator is 100. Both 10 and– the
least common multiple. 100 is a multiple
of both 10 and 100. So we can rewrite this
as something over 100 plus something over 100. This isn’t going to change. This was already 5/100. If we multiply the
denominator here by 10– that’s what we did;
we multiplied it by 10– then we’re going to have to
multiply this numerator by 10. And so this is the
same thing as 10/100. And now we’re ready to add. This is the same thing
as– 10 plus 5 is 15/100. And you could have done that
a little bit quicker just by inspecting this. You would say, look, my
smallest place right over here is in the hundredths place. Instead of calling this
1/10, I could call this literally 10/100. Or I could say this
whole thing is 15/100. And now if I want to reduce
this to lowest terms, we can– let’s see, both the
numerator and the denominator are divisible by 5. So let’s divide them both by 5. And so the numerator,
15 divided by 5, is 3. The denominator, 100
divided by 5, is 20. And that’s about as
simplified as we can get.

Comments (94)

  1. Thanks! Can you do a video about applications of differentiation? Specifically with respect to applied Maximum and Minimum Problems? Thank you

  2. Wow I never thought of it that way ๐Ÿ™‚

  3. Thanks man, YOUR AMAZING!

  4. What kind of sorcery is this you are a magician

  5. thanks you helped me out about please make more videos like this i will like ๐Ÿ™‚

  6. It makes sense now! Mr. Khan, you are a MIRACLE WORKER ๐Ÿ˜€

  7. I didn't understand it

  8. How do you do: .00000987234 I had this problem the last time I did a GED test and I was clueless and didn't understand what to do when it just said do these numbers. There were about ten different ones of this style on the test.

  9. I still don't get it ๐Ÿ™

  10. This helped me a lot thanks ๐Ÿ™‚

  11. wow thanks it helps alot .my math advanced class is doing this I understood already….

  12. Thanks for the help

  13. yay 100 on math homework thx a bunch :0

  14. this really help's a lot i was so confused before seeing this

  15. Thanks for the help, this helps me alot

  16. now that i look at it strat it a good problom

  17. why am i watching this?

  18. i dont even know place value anymore /:

  19. this was very helpful

  20. thank so much do you tutor

  21. couldn't you have gotten 1/4 if you were to simplify again by 3?

  22. i want u as my teacher, ill pay my soul ๐Ÿ˜€

  23. I wish he was my teacher

  24. What!? I am in spirit of math but I don't get it

  25. this help me so much thanks ๐Ÿ˜€

  26. wow great video!!!!!!

  27. 0.15= 15/100= 3/20=150/1000……………………………… UNDERSTOOD!

  28. I hate math ???????

  29. Why are others disliking this video I mean what's wrong with this video he's teaching people mathematics

  30. I cannot understand!

  31. I don't get it can they slow down and explain WHY they are doing it

  32. I don't understand. Another example plse

  33. I had the same problem for my homework ??

  34. i thought this would help me on my math quiz for a grade.

    i plan to fail now.

  35. It's soooooo complicated to comprehend this

  36. Ohh! I was embarrassed to ask my math teacher this because right now I have 101.25 as an average ?
    Thanks for making this video ?

  37. when you don't understand it and you look at every video and finally u understand it

  38. im doing my test and i think i got an F ?

  39. Thanks really helpful ๐Ÿ™‚

  40. Thank you for this

  41. thanks for the help

  42. thx I couldn't call my teacher so…GOOGLE

  43. Why we are multiplying 10 with the numerator and denominator

  44. thanks for the help:D????

  45. can you skip the multiplying and just do the adding?

  46. Dude can u make a video about the concepts of transversal lines

  47. -you don't really make things clear

  48. wait i dont understand so since 100 is bigger than 10 its the common denominator???

  49. Did anyone's teacher show them these videos in 5th? I did. If yes then maybe we went to the same elementary.

  50. It is not a easy way to explain

  51. What if a I have a whole number? It's 2.66

  52. Slow it down man I mean, A LITTLE SLOWER NOT SYFFSBFSGSVSGGSBSBSNdbbehjejebsbhsjdnsbsksk

  53. Are you a teacher? I needed this… Cuz im gr4 and i have a test thats coming up and im having trouble but your making it simple thank you!!!

  54. MATH mental abuse to humans

  55. Best teacher for math goes to khan academy good teaching to school students thank you khan academy

  56. There hss to be a simpler explanation..

  57. i had the same problem

  58. Omg thank. You know I can prove my teacher that I'm not stupid

  59. You make it sound so difficult

  60. this is actually really useful for converting some of the harder fractions atleast for me it is

  61. I have a test on decimals to fractions that I need to know I and thought since it's tommorow this would help but, it seems easier that i just memorize it as the teacher said to do in the first place. When he teaches that and if i dont understand I'll come back.

  62. thanks khan academy

  63. Made this hard asf for no reason. Just put 15/100 and divide both 15 and 100 by 5. Since the last number (5) is in the 100th place you know itโ€™ll be over 100. And youโ€™ll get 3/20 the same way

  64. A lot of people say they are still having trouble getting it. The trick is to watch multiple explanations of one mathematical concept. So watch different explanations of how to convert decimals to fractions. Because one person may explain it in a way you kind of understand, but multiple people will explain it in many ways that you will understand it all.

  65. For those who do not understand. If you have 0.1 as a fraction that is 1/10 if you have 0.25 that will be 25/100 if you have 0.325 that would be 325/1000. Notice the pattern: for every digit you have after 0, that is how many 0's you will add to the 1 as the denominator. Dont forget to simplify the fractions as low as possible.

  66. Love your videos โ˜†โ˜†โ˜†โ˜†โ˜†โ˜†

  67. If you do not understand put Math Antics converting decimals to fractions

  68. Why does he keep the 5 over 100 the second time?

  69. Who else is using this for homweork?

  70. Nobody does this like my teacher?

  71. Pre algebra??!?!? Boi Iโ€™m 6th grade

  72. Thank you I get it now I was so happy till I scream but since I am sick so I canโ€™t very scream(thank you very much)

  73. Everyone getting addicted to word, SO.

  74. CANT UNDERSTAND ANY THING

  75. Thank you ! (๏พ‰โ—•ใƒฎโ—•)๏พ‰*.โœง

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