Multiplying Large Numbers (Traditional Method) Created by: Sabrina Edmondson Adapted from BBC online

Multiplying Large Multiplying Large Numbers (Traditional Numbers (Traditional

Method)Method)

Multiplying Large Multiplying Large Numbers (Traditional Numbers (Traditional

Method)Method)Created by: Sabrina EdmondsonCreated by: Sabrina Edmondson

Adapted from BBC onlineAdapted from BBC online

Multiplying Large Numbers

If this method seems familiar it might be because you were encouraged to use it in school. Talking through the method is far easier than trying to follow written instructions.


Have a look at how the equation 235 x 5 can be worked out using this method.

Step 1: 5 x 5 = 25. Put the 5 in the units column, and carry the 2 to the tens.

H T O2

2 3 5

x 5

5


Step 2: 3 x 5 = 15. Add the 2 makes 17. 7 goes into the ten’s column and carry the 1 to the hundred’s column.

H T O

1 2

2 3 5

x 5

7 5


Step 3: 5 x 2 = 10. Add the carried 1 makes 11.

Th H T O

1 2

2 3 5

x 5

1 1 7 5

So: 235 x 5 = 1,175


Remember to line up the ones, tens and hundreds underneath each other.


Now have a look at the equation:

255 x 25

H T O

2 5 5

x 2 5


First, multiply 255 by the unit digit 5.

Step 1: 5 x 5 = 25. Put the 5 in the units column, and carry the 2 to the tens

H T O

2

2 5 5

x 2 5

5


H T O

2 2

2 5 5

x 2 5

7 5

Step 2: 5 x 5 = 25. Add the 2 makes 27.7 goes into the tens column and carry the 2 to the hundred’s column.


Step 3: 5 x 2 = 10. Add the carried 2 makes 12.

Th H T O

2 2

2 5 5

x 2 5

1 2 7 5


Then multiply 255 by the ten’s digit 2.Remember to place a zero in the ones column first when multiplying the tens.

Th H T O

2 5 5

x 2 5

1 2 7 5

0


Th H T O

1

2 5 5

x 2 5

1 2 7 5

0 0

Step 1: 2 x 5 = 10. Put the 0 in the ten’s column, and carry the 1 to the hundreds.


Step 2: 2 x 5 = 10. Add the carried 1 makes 11.1 goes into the hundred’s column, with 1 carried to the thousands.

Th H T O1 1

2 5 5

x 2 5

1 2 7 5

1 0 0


Step 3: 2 x 2 = 4, add the carried 1 makes 5. The total is 5,100.

Th H T O1 1

2 5 5

x 2 5

1 2 7 5

5 1 0 0


Finally, add down the columns down to get the total.

Th H T O1 1

2 5 5

x 2 5

1 2 7 5

5 1 0 0

6 3 7 5

So: 255 x 25 = 6,375


Remember: Keep the numbers in columns - ones, tens, hundreds etc. When multiplying the tens digit add a zero to the ones column first.

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Multiplying Large Numbers (Traditional Method) Created by: Sabrina Edmondson Adapted from BBC online