Decimal Multiplication

Decimal Multiplication: Write the numbers vertically (you don't have to line up the decimal points in the numbers). Multiply the numbers together as if they were whole numbers.   Count the number of digits to the right of the decimal point in the top number. Count the number of digits to the right of the decimal point in the bottom number. Add the 2 counts together. Place the decimal point in the answer that number of digits from the right.

The following are examples of multiplying decimals.

Multiplying Decimals
	Write the numbers vertically.	Multiply the numbers together	Count digit right of the decimal points.	Place the decimal point in the answer.
12 x 2.3	12        x 2.3	12        x 2.3     36          34      376	12        x 2.3     1     36          34      376      1	12        x 2.3    3 6         34     37.6
23.3 x 2.4	23.3         x 2.4	23.3         x 2.4    932        466   5592	23.3     1         x 2.4     1    932        466   5592       2	23.3         x 2.4   9 32        46 6   55.92
0.123 x 16	0.123          x 16	0.123          x 16    738        1 23     1968	0.123     3          x 16    738         123      1968      3	0.123          x 16    738         123     1.968
0.51 x 0.12	0.51       x 0.12	0.51       x 0.12    102           51      612	0.51     2       x 0.12     2    102           51      612      4	0.51       x 0.12    102           51   .0612

Check Your Understanding

In the following number pairs, how many digits are to the right of decimal points ...

1.   3.67 and 7	Answer 2 digits
2.   12.45 and 11.456	Answer 5 digits
3.   8.2 and 1.3	Answer 2 digits

 

Check Your Understanding

1. Enter two numbers between 0 and 999.999.
2. Think of what you believe the answer should be.
3. Click the button "Check" and check your answer.