Add decimal point equations by using the pencil and paper to figure out the answer. For this example, the equation is 5.234 plus 3.4 equals 8.634. Write down 5.234 as the top number. Underneath this number, write down 3.4, but line up the decimal points.
Multiply decimals by writing down the first number on the top and the multiplier number underneath the top number. You do not need to line up the decimal points. For this example, use 23.5 times 3.21 equals 75.435. You multiply the numbers as you would for an equation without decimal points. When you are done multiplying the numbers and have the answer, you count how many numbers are after the decimal point in both numbers and place the decimal point in that position in the answer. The answer is 75435, but when you count the numbers before the decimal point in 3.21 and the numbers before the decimal point for 25.3, the answer is 75.435, with the decimal point placed three numbers from the right.
Dividing equations with decimal points requires moving the decimal point before dividing the dividend by the divisor. For this example, the equation is .4342 divided by .003. The equation will be in the division format after moving the decimal point the same amount of places as the divisor. Move the decimal point in .003 (divisor) over three places and drop the 00 so you have 3. Move the decimal point over three places on the dividend number (434.2). Now, 434 divided by 3 equals 144 with 2.2 left over. Since 2.2 is not divisible by 3. Place a decimal point after 144 (144.) and move the decimal point over one place to the right of the second 2 so you have 22. Divide 22 by 3 for an answer of 7 after the decimal point (.7) and an answer of 144.7 with a remainder of 1.