1. Multiplication

2. Remember to put a zero in the empty place.
Multiplying by 10 H T U 4 5 X 1
When you multiply by 10, all the digits move one place to the left. 4 5
Remember to put a zero in the empty place.
Remember: A quick way to multiply a whole number by 10 is to put a zero on the end.
© 2006 Paul Howarth

3. Fill up the two empty places with two zeros.
Multiplying by 100 Th H T U 4 5 X 1
When you multiply by 100, all the digits move two places to the left. 4 5
Fill up the two empty places with two zeros.
Remember: A quick way to multiply a whole number by 100 is to put two zeros on the end.
© 2006 Paul Howarth

4. Multiplying large numbers
Look at this example: Th H T U 2 3 7 X 5
Step 1: Start with the units.
5 x 7 = 35.
Put 5 in the units column and carry the 3 into the tens. 1 1 8 5 1 3
Step 2: Now the tens. 5 x 3 = 15.
Add the 3 you carried to get 18.
Put 8 in the tens column and carry the 1 into the hundreds.
Step 3: Now the hundreds. 5 x 2 = 10.
Add the 1 you carried to get 11.
Write 1 in the hundreds column and 1 in the thousands.
© 2006 Paul Howarth

5. Multiplying large numbers
Now look at this example:
TTh Th H T U 2 3 7 4 5
Step 1: Multiply 237 by 5 just like we did last time.
Step 2: The 4 is in the tens column so has the value 40. x 1 1 1 8 3 5
To multiply by 40, we multiply by both 10 and 4. + 9 1 4 2 8
Put a zero in the units column to multiply by 10. 1 6 6 5
Now multiply by 4. 1
Step 3: Add to get your answer.
© 2006 Paul Howarth

6. Multiplying large numbers
TTh Th H T U 2 3 7 4 5
The two most common mistakes. x 1 1 1 8 3 5
1. Forgetting this zero. + 9 1 4 2 8 1 6 6 5 1
2. Getting the carrying figures muddled up – keep them separate.
© 2006 Paul Howarth

7. Lattice method 2 3 7 4 5 Here is another way to multiply 237 x 45.
We are multiplying a three digit number by a two digit number, so draw a table with 3 columns and two rows like this:
Now put 237 across the top and 45 down the right hand side. 2 3 7 4 5
© 2006 Paul Howarth

8. Lattice method
Now fill in the squares by multiplying.
2 x 4 = 8
(no tens and 8 units)
3 x 4 = 12
7 x 4 = 28 2 3 7 2 1 4 8 2 8 1 1 3 5 5 5
7 x 5 = 35
2 x 5 = 10
3 x 5 = 15
© 2006 Paul Howarth

9. Don’t forget the 1 you’re carrying!
Lattice method
Now add up following the diagonal lines: 2 3 7 2 1 4 8 2 8 1 1 3 5 5 5 1 1 1 6 6 5
Don’t forget the 1 you’re carrying!
So 237 x 45 = 10665
© 2006 Paul Howarth