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### Course: 4th grade > Unit 4

Lesson 1: Multiply by 10s# Multiply by 2-digit numbers: FAQ

Frequently asked questions about multiplying by 2-digit numbers.

## What's the point of estimating products?

Estimating can help us get a rough idea of what the product might be before we start multiplying. This way, we can catch any mistakes early on.

Try it yourself with this exercise:

## How can we use area models to multiply 2-digit numbers?

We can break down each number into its place values (tens and ones) and draw an area model to show the different parts. This will help us see how the numbers multiply together.

Try it yourself with this exercise:

## How can we use partial products to help us multiply?

When we multiply two $2$ -digit numbers using partial products, we break down each number into its tens and ones place values. We multiply each place value separately, and then add the four partial products together to get the final product.

For example, let's multiply $73\times 42$ .

Try it yourself with this exercise:

## What are some common mistakes to watch out for when multiplying 2-digit numbers?

It's important to keep track of the place values when we multiply 2-digit numbers. Sometimes, we might accidentally add instead of multiplying, or forget to carry over a number.

Try it yourself with this exercise:

## Want to join the conversation?

- For those who don't understand, this method of multiplication is supposed to be done mentally. This is one of many ways to do math. Some prefer carrying over numbers on paper, while others prefer doing it mentally. So, this method is for people who want to do be really good at math without a calculator, a paper or a pencil. This method is called "partial products".(11 votes)
- Oh, that Kinda Makes sense thanks for all your help!(3 votes)

- how do you do 500x136=?(5 votes)
- You would do 136x100 to get 13,600 then you would do that times 5 to get 68,000(3 votes)

- What's 12 multiply by 85(4 votes)
- the answer is

1020(2 votes)

- how do you have 838(3 votes)
- I think it is 838X1(2 votes)

- What's the point of estimating products?(3 votes)
- Estimating can help us get a rough idea of what the product might be before we start multiplying. This way, we can catch any mistakes early on.(1 vote)

- This does not make sense bc like you have to multiply and then add. I don't get it.(2 votes)
- What he did was breaking up some number into its place values. For example 63 = 60 + 3.

With a simpler example, if you had 63*12, you can multiply the 60 by 12 and the 3 by 12. This would then mean you have to add those results together, since you broke it up before.

60*12 = 720

3*12 = 36

Now you add these: 720 + 36 = 756.

Hope this helped!(3 votes)

- what is 1465 divided by 31(2 votes)
- how can I get better at math?(2 votes)
- you can do Khan Academy more(1 vote)

- Thanks for the help but I Still don't get It can you help me some more.(2 votes)
- I have a question because...

My teacher has us write the 0s not (6tens x 7hundreds) and my problim is that I keep geting 100% but I forget to add the 0s and thats why I keep notes. thank you!9:38(2 votes)