So slightly off-topic... I quit marijuana recently, and as I do these exercises and get further into Khan Academy, I keep wondering if people can do these exercises easily in their head. Give me a pen and paper and these problems are like nothing, because I understand them conceptually, but in my head I can barely keep track of the answers generated at each step. Just curious if I'm the only one that needs a pen and paper for this simple stuff.

Some people can do these kinds of things in their heads, but don’t beat yourself up if you can’t. It gets easier with practice and as you find your own shortcuts. :)

I now how to do it but I can't do it sideways I now it doesn't mater if it is sideways or not

Do it the way that makes it easier for you...but sometime in your life you will have to learn it sideways

so when you line up all the numbers will you subtract left to right or the other way around??

Like any regular subtraction problem, you will subtract right to left.

Main content

MAP Recommended Practice

Course: MAP Recommended Practice > Unit 42

Lesson 12: Subtracting decimals

Subtracting decimals: 9.57-8.09

Name: Subtracting decimals: 9.57-8.09
Uploaded: 2013-12-27T22:16:42Z
Description: To find the least common denominator of two fractions, we can either list out the multiples of the two denominators until we find a common one, or use prime factorization. Once we've found the least common denominator, we can rewrite the fractions so they both have this denominator, and then add them together.

Google Classroom

To find the least common denominator of two fractions, we can either list out the multiples of the two denominators until we find a common one, or use prime factorization. Once we've found the least common denominator, we can rewrite the fractions so they both have this denominator, and then add them together. Created by Sal Khan.

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eye_travis
Posted 2 years ago. Direct link to eye_travis's post “So slightly off-topic... ...”
So slightly off-topic...

I quit marijuana recently, and as I do these exercises and get further into Khan Academy, I keep wondering if people can do these exercises easily in their head. Give me a pen and paper and these problems are like nothing, because I understand them conceptually, but in my head I can barely keep track of the answers generated at each step.

Just curious if I'm the only one that needs a pen and paper for this simple stuff.
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- Johanna
  Posted 2 years ago. Direct link to Johanna's post “Some people can do these ...”
  Some people can do these kinds of things in their heads, but don’t beat yourself up if you can’t. It gets easier with practice and as you find your own shortcuts. :)
  Comment on Johanna's post “Some people can do these ...”
  (10 votes)
ProJorden💎🦄💎🐢🐢🐢🐢🐢🐢
Posted 9 years ago. Direct link to ProJorden💎🦄💎🐢🐢🐢🐢🐢🐢's post “I now how to do it but I ...”
I now how to do it but I can't do it sideways I now it doesn't mater if it is sideways or not
Button navigates to signup pageComment on ProJorden💎🦄💎🐢🐢🐢🐢🐢🐢's post “I now how to do it but I ...”
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- Toby Harris
  Posted 3 years ago. Direct link to Toby Harris's post “Do it the way that makes ...”
  Do it the way that makes it easier for you...but sometime in your life you will have to learn it sideways
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  (3 votes)
Justin Alfaro 0v0
Posted 5 months ago. Direct link to Justin Alfaro 0v0's post “Here's a question, what's...”
Here's a question, what's 95.23 minus 56.54? This may be easy to know so here it is! You take away the two to make it into one, and the three becomes 13 so 13 minus 4 is 9. You take away one number from five to four and then the one becomes into 11, and, 11 minus 5 is 6. You take away one number from nine to eight and the 4 becomes into 14, so 14 minus 6 equals 8. This is the last and most simple but not least, 8 minus 5 and it's 3! So, the answer was 38.69, and there it is!
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Hydius
Posted a month ago. Direct link to Hydius's post “tôi là người vietnam”
tôi là người vietnam
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armyozone21
Posted a month ago. Direct link to armyozone21's post “the answer is not the asw...”
the answer is not the aswerrrrrrrrrrrrrr
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🦋🪬Denise🪬🦋
Posted 8 months ago. Direct link to 🦋🪬Denise🪬🦋's post “We never got are gifts fo...”
We never got are gifts for khan for hitting one hundred.
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🤨📸📸📸📸📸📸📸📸📸
Posted 4 months ago. Direct link to 🤨📸📸📸📸📸📸📸📸📸's post “khan academy Incredible A...”
khan academy Incredible Answer%
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ellen.williams
Posted 10 days ago. Direct link to ellen.williams's post “this is confusing and i d...”
this is confusing and i dont understand
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EFHaas05😂
Posted 9 years ago. Direct link to EFHaas05😂's post “so when you line up all t...”
so when you line up all the numbers will you subtract left to right or the other way around??
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(2 votes)
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- Johnson
  Posted 9 years ago. Direct link to Johnson's post “Like any regular subtract...”
  Like any regular subtraction problem, you will subtract right to left.
  Comment on Johnson's post “Like any regular subtract...”
  (3 votes)
JosiahRamesar
Posted 9 years ago. Direct link to JosiahRamesar's post “Great video and now I rea...”
Great video and now I really now how to subtract decimals. Thank you?
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(2 votes)
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Video transcript

Let's try to subtract 9.57 minus 8.09. So try to pause this video and figure this out first before we work through it together. All right. Well, let's just rewrite it. Let's rewrite it. And when I rewrite it, I like to line up the decimals. This one it's a little intuitive. We have 8.09. Just like that, and now we're ready to subtract. And we want to subtract 9 hundredths from 7 hundredths. Well, we don't have enough hundredths up here so let's move over here. Let's see if we can do some regrouping so we always have a higher number on top. So over here we want to subtract 0 tenths from 5 tenths so we have enough tenths over here. So let's regroup. So instead of 5 tenths, I'm going to have 4 tenths, and then I'm going to give that other tenth, which is the same thing as 10 hundredths over here, so this becomes 17 hundredths. 17 minus 9 is 8. 4 minus 0 is 4. And then I have 9 minus 8 is 1. So this is going to be 1.48.