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Lesson 2: Converting fractions to decimals

# Fraction to decimal with rounding

Sal writes 16/21 as a rounded decimal. Created by Sal Khan.

## Want to join the conversation?

• what does he mean at
• I know this wuestion was asked 10 years ago but i understand others may be confused as well so i’ll try my best to answer this.

Sal is saying to divide 16 by 21. Now this is because the denominator is greater than the numerator so to find the decimal, we divide 16 by 21. An easy way to remeber this is because when the numerator is greator than the denominator, it will always be 0.something. That’s how we find the decimal version.

I hope this was helpful have a great day everyone!
• could you do this with negative numbers? like:

-45
-------
-9
• Yes you could, the two negative signs would cancel out to a positive sign, and 45/9 is simply five, so the answer would be five
• Is there a quicker and more efficent way of doing this instead of going through the whole process of long division ?
• you can just divide the top number by the bottom one
• i saw a raccoon at a tree
• Why does he decide to round to the nearest ten thousandths, is there some sort of rule to use when dividing and deciding what to round to?
• what is this?? How do you do this??
• you can divide the top number by the bottom number or you can do what he is doing. its I little confusing for me tho because I learned this all in french but I have a good understanding of this but if the bottom number is bigger then the top number then you know the answer will be less then 1 because it cant make exactly or over one so there will be a 0. before your answer.
• how does he calculate that fast?
• Years and years of practice and doing math over and over.
• I should def probably stop scrolling thro comments and start actually watching the vid lol
• How many zeros did I need to add? and why sometimes just add three zeros? sometimes add five zeros?
• You can add as many as you like, or as many as you need when you're dividing past the decimal place.
3 zeros tend to be handy, it depends on how accurate you want the result to be

So if you want an accurate result, say 45.2836709239......... You'll want a lot of zeros. But usually you don't need a result that accurate, so maybe just use three zeros, unless otherwise told to. Most of the time they just want you to round to 2 zeros. For example 45.28