Basic Mathematics

Addition of Decimals

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Addition of Decimals

Adding decimal numbers is the same as adding whole numbers. However, you must be careful to align numbers so that you are adding like place values. Do this by lining up the decimal point of each of the addends in a problem.

7.146 + 0.32 + 4 = _____

Rewrite with the decimal points aligned, and then add each column beginning from the right:

Addition of Decimals

Adding zeros to the right of a decimal number does not change its value:

1.3 = 1.30 = 1.300

It is easier to add when all addends have the same number of decimal places, so add zeros as placeholders in empty decimal columns.

Addition of Decimals

Click on the sum.

35.2
+ 28.4

Question 1 of 8

63.6 is the sum.

The sum in the ones place is incorrect. 5 + 8 =13. Try again.

The sum in the tens place is not 5. Be sure to regroup 1 ten from the ones column. Try again.

One of these numbers is the sum. Try again.

Add each column from right to left, and bring down the decimal point.

Addition of Decimals

Click on the sum.

6.717
+ 0.55

Question 2 of 8

The digit in the ones place is not 6. Be sure to regroup 1 one from the tenths column. Try again.

You are not adding like place values. Begin by putting a zero under the 7 and adding 7 + 0. Try again.

7.267 is the sum.

The sum in the thousandths place is missing. Put a zero under the 7 and add 7 + 0. Try again.

One of these numbers is the sum. Try again.

Rewrite 0.55 as 0.550, and then add each column from right to left.

Addition of Decimals

Click on the sum.

$30.03
57.
+ 0.99

Question 3 of 8

The digit in the ones place is not 7. Be sure to regroup 1 one from the tenths column. Try again.

The digit in the tenths place is not 1. Be sure to regroup 1 tenth from the hundredths column, and then add 1 + 9. Try again.

Begin in the hundredths column by adding 3 + 0 + 9. Try again.

$88.02 is the sum.

Rewrite $57 as $57.00, and then add each column from right to left.

Addition of Decimals

Click on the sum.

     8.77
   14.033
     0.0008
+ 16.

Question 4 of 8

Begin in the ten-thousandths place and add 0 + 0 + 8 + 0. Then add 0 + 3 + 0 + 0 thousandths. Try again.

38.8038 is the sum.

The ten-thousandths place is correct. Next add 0 + 3 + 0 + 0 in the thousandths column. Try again

Begin in the ten-thousandths place and add 0 + 0 + 8 + 0. Try again.

One of these numbers is the sum. Try again.

Rewrite 16 as 16.0000, and then add each column from right to left.

Addition of Decimals

There are four questions remaining. In each of these questions, the addition is presented in horizontal form. You should line the numbers up in vertical columns before trying to find the sum.

Addition of Decimals

Click on sum.

$73.54 + $13.47 =______

Question 5 of 8

The digit in the ones place is incorrect. Be sure to regroup 1 one from the tenths column. Try again.

The tenths digit is incorrect. Be sure to regroup 1 tenth from the hundredths column and add 1 + 5 + 4. Try again.

The hundredths digit is correct. Next, regroup 1 tenth from the hundredths column and add 1 + 5 + 4. Try again.

$87.01 is the sum.

One of these numbers is the sum. Try again.

Write the addends vertically with the decimal points lined up.

Addition of Decimals

Click on sum.

27.749 + 93.42 =______

Question 6 of 8

The digit in the ones place is incorrect. Be sure to regroup 1 one from the tenths column and add 1 + 7 + 3. Try again.

You may not be adding like place values. Write the second addend under the first with the decimal points lined up. Try again.

121.169 is the sum.

You may not be adding like place values. Write the second addend under the first with the decimal points lined up. Try again.

One of these numbers is the sum. Try again.

Write the addends vertically with the decimal points lined up.

Addition of Decimals

Click on sum.

683.1 + 229 + 0.008 =______

Question 7 of 8

912.108 is the sum.

You may not be adding like place values. Remember that 229 is a whole number and should be written as 229.000 with the decimal point lined up under the decimal point above. Try again.

The first digit of the sum (8) belongs in the thousandths column, not the hundredths column. Try again.

Begin in the thousandths column by adding 0 + 0 + 8. Try again.

One of these numbers is the sum. Try again.

Write the addends vertically with the decimal points lined up. Remember that 229 and 229.000 have the same value.

Addition of Decimals

Click on sum.

385.625 + 0.25 +1.01 =______

Question 8 of 8

Begin in the thousandths column by adding 5 + 0 + 0. Try again.

The digit in the tenths place is incorrect. Add 6 + 2 + 0 tenths. Try again.

386.885 is the sum.

One of these numbers is the sum. Try again.

Write the addends vertically with the decimal points lined up.

Multiplication of Decimals