91热爆

Watch: Multiplying 2 digits by 1 digit

When multiplying a 2-digit number by a 1-digit number you can use both mental and written methods.

Let's take a look at an example of solving a multiplication problem in your head. Before you press play have a think about how you would work out 19 x 5 ?

Back to top

Mental method for multiplication

Top tip

You can do this by breaking down a number. Let's think about an example:

What is 6 x 40?

6 x 40 is equal to 6 x 4 x 10

Let鈥檚 focus on answering 6 x 4 first.

6 x 4 = 24

Now you can multiply 24 by 10. When you multiply by 10, all the digits move one space to the left and a zero is placed in the ones column to represent to number increasing in value.

24 x 10 = 240

Top tip
Back to top

Written methods

Did you know?

Sometimes it might be easier to use a written method to work out a 2-digit by a 1-digit multiplication.

We call this method short multiplication.

Did you know?
Back to top

Example 1

What is 48 x 6?

When you set out short multiplication, it is important to make sure the place value of the digits are in the correct place.

Put the 4 in the tens column and the 8 in the ones column.

Like this:

Step 1

Just like when you solve column addition and subtraction, you start with the digits in the ones.

8 x 6 = 48

Since 48 is 4 tens and 8 ones, you have to remember to keep the place values in the correct column. The 8 stays in the ones column, while you carry the 4 into the tens column.

Step 2

Time to work out 40 x 6 now.

40 x 6 = 240

But you can鈥檛 forget about the 4 tens that you carried over - you need to remember to add that on to the answer.

240 + 40 = 280

Again, make sure everything is in the correct place value column.

48 x 6 = 288

Back to top

Example 2

Beverley ordered 8 packets of balloons. Each packet contained 52 balloons. How many balloons has she got in total?

The equation we are working out is:

52 x 8

First, set the multiplication out correctly:

52 x 8 as a short multiplication

Step 1

Now the multiplication is set out correctly, you can solve the multiplication in the ones column.

2 x 8 = 16

Remember to carry the 1 into the tens column.

Step 2

Now it's time to work out 50 x 8

50 x 8 = 400

Don鈥檛 forget about the ten you carried over: 400 + 10 = 410.

52 x 8 = 416

Beverley now has 416 balloons.

Back to top

Activity

Quiz

Now you've learned the different methods for multiplying a 2-digit by a 1-digit number see if you can solve these calculations.

Back to top

NEW! Play Guardians: Defenders of Mathematica - the Halloween update. game

Experience Mathematica as you鈥檝e never seen it before, with all-new backgrounds and costumes for Halloween. Available for a limited time only. Use your maths skills to save the day before it's too late!

NEW! Play Guardians: Defenders of Mathematica - the Halloween update
Back to top

More on Multiplying and dividing

Find out more by working through a topic