1. when dividing decimals, what must you do if there is a decimal in the divisor? 2. when adding or subtracting two decimals, what is the first thing you must do? 3. when multiplying decimals, how do you determine where to place the decimal in the answer?

1. you must move the decimal the amount of digits until the divisor is a whole number. This also means that you move the decimal for the dividend too, adding zeros where it is needed.
2. you must first figure out where the decimal is, so that you will find out what place value each digit is, allowing you to add correctly. For example 10.52 + 0.048 = 10.568
3. you determine it by the amount of digits from the right it is, and moving it to the correct place. For example 10.5 x 20.25 = 212.625 (note that for this example, the decimal moved to the left 3 spaces)

hope this helps