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## 5th grade

### Course: 5th grade > Unit 8

Lesson 3: Multiplying decimals- Developing strategies for multiplying decimals
- Multiply decimals tenths
- Developing strategies for multiplying 2-digit decimals
- Multiply decimals (1&2-digit factors)
- Multiply decimals (up to 4-digit factors)
- Multiplying decimals (no standard algorithm)
- Multiply decimals: FAQ

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# Multiplying decimals (no standard algorithm)

CCSS.Math:

We'll start with simple problems like 0.9 x 0.2 and build to more complex problems like 3.4 x 6.1.

In this article, you'll learn how to multiply decimals by jumping in and giving it a try without being shown how to do it first.

The problems go from easier to more difficult. Along the way there are examples and explanations to help you out if you get stuck. If you get a little confused, just think of it as a chance to learn!

Let's start by multiplying two tenths together.

### Problem set 1:

Beautiful, let's move on to multiplying whole numbers by tenths and hundredths.

### Problem set 2:

Great, let's finish with a few more challenging problems.

### Problem set 3:

## Want to join the conversation?

- When we convert a decimal into a fraction, how do we know/ what do we write the fraction as? Is it over 10 or 100, and how do we determine that?(44 votes)
- it depends how much digits are behind the decimal point like 0.5 is 5/10 and 0.05 is 5/100

0.005 is 5/1000 and so on(12 votes)

- this is how you multiply decimals ....

lets do 0.5x0.5

FIRST you just do 5x5 which is 25....this the easy way....

THEN after you do 5x5 which is 25, then count the decimals place which is 2 places.....so move 25 which is 25.0 2 times to the left so you get 0.25

IS THE ANWSER 0.25

PLZ COMMENT BELOW(23 votes)- nice i comment below(2 votes)

- Why is this called Khan Academy.(20 votes)
- It’s named after someone(2 votes)

- Hi.....if you need help plz comment your question...thank you(15 votes)
- hey is anyone really good at math on khan.(7 votes)
- I am, is there anything I can do to help you?(4 votes)

- how can you do the decimal part? when you times them all i get them wrong it's confucesing(5 votes)
- When we turn a decimal into a fraction, how do we know what to write the fraction as? Is it over 10 or 100, and how do we determine that?(4 votes)
- if the places after the decimal point is 2 the denominator is 100 if the places after is 1 , the denominator is 10. If the places are 3 the denominator is 1000.

ex*

0.8 = 8/10

0.80 = 80/100

0.800 = 800/1000(1 vote)

- an issue i've had is with confusion in multiplying the thousandths place and so on, is there an easier way of dealing with that or thinking about how to solve it?(5 votes)
- Try to make it an integer and then multiply and then divide by (whatever you multiplied by in order to get an integer) at the end. For example, 0.123 x 0.234 -> 123 x 234 = 28782 -> 28782/(1000*1000) = 0.023782(0 votes)

- what is 1999999999999999x9999999999999999(4 votes)
- It really tricky when you multiply decimal even though the number get smaller.(3 votes)