How_To_Be_Good_At_Math

125

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CALCULATING • MULTIPLYING DECIMALS

We’ll multiply

each digit on the

top row by 5

Write a

decimal point

on a new line

1 carried into

the next column

Multiply 3 by 5

Multiply 6 by 5

The 1 carried is

added to the

number put in

this column

Add the two lines in

the answer together

This 5 means

5 tens or 50

Put a 0 on a

new line as

a place holder

Now multiply 3 by 5. The answer

is 15. Write the 5 in the column to

the left of the decimal point. Carry the

1 into the next column to add on at the

next stage.

Next, multiply 6 by 5. The answer

is 30. Add the 1 ten carried over

from the previous step to make 31. Write

1 in the next available column and the 3

in the next column to the left.

Now we have multiplied each of

the digits on the top row by all

of the digits on the bottom row, we add

the two lines in our answer together:

12.6 + 315.0 = 327.6

So, 6.3 × 52 = 327.6

Now we’re going to multiply all the

digits on the top row by 5 and write

the answers on a new line. Write a

decimal point on this new line, in line

with the other decimal points.

When we multiply by this 5, we’re

actually multiplying by 50, which is

10 times 5. So, we put a 0 in the first

column on the new line as a place holder.

6.3 × 52 = 327.6

1

.

.0

5.0

(^12) .6
6.3
52
12 .6
12 .6
.6
.0
12
12
315
315
327
6.3
52
6.3
52
6.3
52
6.3
52
.6
.0
.6
1
1
124-125_Multiplying_decimals.indd 125 29/02/2016 18:56