Khan: Subtracting decimals example 2

Using paper and pencil. What is 39.1 - 0.794 ?

• 38.308

• 39.606

• 38.306

• 39.694

When subtracting decimals, does it matter which number goes on the top?

• yes

• no

• sometimes

Where should the zero go?

• under the 3

• under the 1

• under the 9

Why is it important to line up the decimals?

• to make sure the place values are in the correct position

• to not get confused by the numbers

• to make sure the zero is taken out of the problem

Good question - How would you subtract from nothing?  What do you have to fill in the empty place values with?  

• Leave it alone. It just means that you drop down the 9 and 4.

• Fill them with zeros in order to hold those place values.

• Fill them with number that you can subtract 9 and 4 from.

He chose to regroup this way at the start of the problem . Doing all his regrouping at once. 

Which number could he have chosen to regroup from later on?

• 9

• 1

• 0

Using paper and pencil, solve 700.18 - 44.102

• 656.160

• 744.082

• 259.160

• 656.078