Operations with Decimals
Adding 2.5 + 3.7 is just like adding 25 + 37, except the decimal point sits in a different place. Understanding place value makes decimal operations straightforward.
Addition and subtraction
Line up the decimal points. Add or subtract as you would with whole numbers. Bring the decimal point down to the answer. 2.5 + 3.7 = 6.2. Works the same for subtraction.
Multiplication
Multiply as if there are no decimal points. Then count the total decimal places in the factors and place the decimal point that many places from the right in the product. Example: 2.5 × 3.7 = 9.25 (one decimal place + one decimal place = two decimal places in the answer).
Division
If dividing by a whole number, use long division and bring the decimal point straight up. If dividing by a decimal, move the decimal point in both numbers to make the divisor a whole number. Example: 9.25 ÷ 2.5 becomes 92.5 ÷ 25 = 3.7.