Multiplying One-Digit by Two-Digit Numbers

Great job learning your multiplication facts in the last lessons.

Let's test how fast you can multiply this:

5 x 6=?

What's the answer?

That's right!

It's 30!

What about this?

4 x 7=?

That's right!

It's 28!

Now, it's time for you to learn how to **multiply a 1-digit number by a 2-digit number.**

Let's say you have to multiply 21 x 5:

21 x 5=?

We could add 21 to itself, 5 times.

21 + 21 + 21 + 21 + 21=105

That gives us 105.

But it doing that takes so much time.

Here's a better way to solve this equation.

The **column form** is the most common way to solve 2-digit by 1-digit multiplication problems. This is also called the **standard method**.** **

**First,** arrange the numbers in **column form**.

π **Tip:** Write the **2-digit **number at the **top,** and the **1-digit **number at the** bottom. **Also, remember to **align the place values **correctly.

**Then,** we start multiplying with the numbers on the right.

We multiply 5 x 1.

5 x 1=5

π We write 5 in the ones place.

**Next,** we multiply 5 by 2.

5 x 2=10

We write 10 before 5.

That gives us **105.**

That's the answer!

Why don't you try multiplying this:

8 x 97=?

What should we do first?

That's right!

**π First,** we write the numbers **in column form.**

We write 97 at the top, and 8 at the bottom.

**π Then,** we **multiply from right to left.**

We start with 8 x 7.

8 x 7=56

Now, we don't just write 56.

Instead, we write 6 in the ones place.

And we carry 5 to the tens place.

What do we do next? π€

**π Next,** we multiply 8 x 9.

8 x 9=72

π But remember, we carried over 5 to the Tens place.

π So, we have to add that to 72.

**IMPORTANT:** Only add the carry over part (5) **AFTER **you've multiplied (8 x 9).

72 + 5=77

We write 77 before 6.

Our answer is **776****. **

Try to multiply this:

6 x 39=?

What answer did you get?

You're correct!

It's 234!

This is how we got the answer:

Great work!Β

Now, you can move on to practice. πͺ

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