Decimal numbers

• Mathematics
• 6th Grade

Adding and Subtracting Decimals

Adding and Subtracting Decimal Numbers

2.59 + 3.1              4.75 - 3.212

Remember, decimals are another form of fractions

0.1 = one tenth

0.21 = twenty-one hundredths

0.8005 = eight thousand, five ten-thousandths

1.5 = one and five tenths

5.099 = five and ninety-nine thousandths

6.985 = six and nine hundred eighty-five thousandths

Remember that adding zeros to the right of a decimal number does not change its value.

5.3 = 5.300

1.9 = 1.90

0.05 = 0.050

Any regular number can be written as a decimal number.

Just add a decimal point and zeros to the right!

5 = 5.0 =5.000

250 = 250.00 = 250.0000000000000000000000000000

Five and five-tenths

Nine-hundredths

0.09

0.090

5.50

5.500

0.050

0.0050

55.0

0.9

0.900

1.090

To add decimal numbers...

1) line up the decimal points

2) fill spaces on the right side

with zeros

3) add

Don't forget to carry when you need to!

    55.9 + 41.339

 

    55.9

 + 41.339

     

    55.900

 + 41.339

    97.239

To subtract decimal numbers...

1) line up the decimal points

2) fill spaces on the right side with zeros

3) subtract.

Don't forget to borrow when you need to!

48.95 - 7.2581

48.95

-  7.2581

48.9500

-  7.2581

  41.6919

What if a number doesn't have a decimal point?

Add a decimal point and zeros to the right before adding or subtracting.

52 - 4.899

 52                                             

- 4.899

52.000

-4.899

What steps do we do before adding or subtracting decimal numbers?

Drag each problem to the step that needs to be done next

1. Line up decimal points

2. Add zeros to fill spaces

on the right side

3. Add or subtract!

 

 5.99

+1.03

45.99

-  1.1  

 

 55.099

-1.06    

598.2

+9.0599

59.23 - 13.99

1. 4524
2. 45.24
3. 46.34
4. Cannot be subtracted

510.05 + 2.995