How to multiply a three digit decimal by a one digit decimal number (for
example 0.529 * 0.7):
- Place one decimal above the other so that they are lined up on the right
side. Draw a line under the bottom number. Temporarily disregard the
decimal points and multiply the numbers like multiplying a three digit
number by a one digit number.
- Multiply the two numbers on the right side. (9 * 7 = 63). This number is
larger than 10 so place a six above the center column and place three
below the line in the right column.
- Multiply the digit in the top center column (2) by the digit in the
center of the right column (7). The answer (2*7=14) is added to the 6
above the center column to give an answer of 20. The units place value (0)
of 20 is placed below the line and the tens place value (2) of the 20 is
placed above the five.
- The five of the top number is multiplied by the seven of the multiplier
(5*7=35). The two that was previously carried is added and 37 is placed
below the line. At the start we disregarded the decimal places. We must
now count up the decimal places and move the decimal place to its proper
location. We have three decimal places in 0.529 and one in the decimal 0.7
so we move the decimal four places to the left to give the final answer of