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### Course: Arithmetic (all content)>Unit 6

Lesson 1: Intro to decimals

# Decimal place value

Sal introduces decimal numbers and understanding place value to the right of the decimal.

## Want to join the conversation?

• How do you divide a fraction?
• Let’s say you have a problem on your test that says 7/8 divided by 1/3.
First of all, let’s find out the reciprocal of 1/3. A reciprocal is a reversed fraction, so the reciprocal for 1/3 is 3/1.
Now you multiply 7/8 by 3/1.
To multiply a fraction, multiply numerator and demoninator, so 7/8 x 3/1 equals 21/8, which is an improper fraction. To make it proper, you must know how many times 8 fits into 21, which is 2, because 2 x 8 equals 16, but 3 x 8 equals 24, so it’s bigger than 21. Now we do 21 minus 16 to figure out the rest of the fraction. So we know that 21 - 16 = 5, and the denominator of 21/8 stays the same, so we have the mixed number 2 5/8.

So 7/8 divided by 1/3 equals 2 5/8.

*and also the video is about decimal place value and we are so off-topic right now 😅
• Why are decimals are so important and where and how do we use them?
• Decimals are important because as you get into more advanced math, you'll be finding squareroots of numbers that aren't even. Among other things along that line.
• Can there be negative decimals?
• Yes, we can attach a negative sign in front of any decimal to make it negative.

Have a blessed, wonderful day!
• is there such thing as oneths?
• No, once you have 10 tenths you will have 1 whole.
Just like if you were to go from 9 to 10. We would start at the ones place and move to the tens place by going up. The same thing will happen if we go down:

we start at 1 and go down instead of up but, we don't want to head into the negative part of the number line so we go to 1 tenths instead.

So, if you had oneths that would mean you have a whole number in the ones place.

So, there is no such thing as "oneths"
• what is a reciprocal?is it a fraction or a decimal?
• A reciprocal is like taking number 90 and adding one to the end like 190 and adding a slash in between the numbers like 1/90.

Take 5. Add 1 to the end to get 15. Add a slash: 1/5. Turn it into a decimal: 0.2, and there you have it. 1/2 equals 0.5, and 1/5 equals 0.2, crazy right!?
• i know what decimals are, but what can you do with them? all i know is that decimals are um instead of 235 your adding a decimal point and a 0.4 or 4/10 so its 235.4
• Everything to do with money uses decimals. So, you will be using them your entire life.
• How large can a decimal get?
• Like regular whole numbers it can be as small or as big as you want.
It can be 0.999999999999999999999999999999999999999999999999999999999999999999 and you can get as close to 1 as you want by adding more 9s. Or go really small and write something like 0.00000000000000000000000000000000000000000000000000000000000000000000001 and get closer to 0 by adding more 0s between the . and 1. A decimal can be any amount between 0 and 1.
• Why is there no oneth space in decimals?