I don’t know how to do this .

Step-by-step explanation:

Start at the left side and work your way over.

3 x 1 + 9 should be easy.  3 x 1 = 3 then + 9 = 12

The question says to report the answer as a decimal so now is the perfect time to convert those fractions into decimals.

1/10 = 0.1

1/100 = 0.01

1/1000 = 0.001

The columns are the same as whole numbers ( tens, hundreds, thousands, etc) except they go in the opposite direction (to the right instead of left).

The first column after the decimal is the tens; second column is hundreds and so on.

Back to the problem.  So far we did the first 3 numbers and are at the number 12.

Now you will multiply 12 and 0.1.  This answer is 1.2 which just moves the decimal place one spot toward the left.

Next you are adding 2 to the above number.  2 + 1.2 = 3.2

Now you are multiplying this number and 0.01.  Again it is just moving the decimal to the left but by two steps this time.  You'll have to add a zero in front of the 3 in order to do this so you now have 0.032

Again we will add 2 to this number which will now give you 2.032

Multiply this number and 0.001 which again moves the decimal to the left but 3 spaces this time.  Again you'll have to add zeros in front of the 2 in order to do this.  You end up with 0.002032

21

step-by-step explanation: