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 ?
Mental method for multiplication
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
Written methods
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.
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
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:
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.
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.
NEW! Play Guardians: Defenders of Mathematica - the Halloween update. gameNEW! Play Guardians: Defenders of Mathematica - the Halloween update
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!
More on Multiplying and dividing
Find out more by working through a topic
- count23 of 36
- count24 of 36
- count25 of 36
- count26 of 36