Where would you place the decimal point in this product? 9.412 multiplied by 100=9412

This is a multiple choice question and the alternatives are as follows a. 9.41200 b. .09412 c.94.12 d.941.2

1 Answer
Nov 25, 2017

You can often place decimal points by using logic.


The math problem was approximately

#9 xx 100#

So the logical answer has to be around 900.

So locate the decimal point to make the answer about 900
-- not 90 or 9000.

d. 941.2

If you can't estimate exactly enough, here is a plan that always works:

1) Start with the question
Count the total number of decimal places of both numbers in the original question.

2) Then look at the answer
Starting on the right of the answer, and counting backwards to the left, count off the same number of places.

3) That will always be where the decimal point goes.

Multiply #2.16 xx 14.328#

To locate the decimal point, start at the question.
Count the TWO decimal places in #2.16# plus the THREE decimal places in #14.328.#

That is a total of five decimal places.

Then look at the answer
Starting at the 8 at the end of the answer, count back five places.
That lands you between the 0 and the 9, which is where to put the decimal point.
So you write the answer like this:

But anyway, you should have figured this out by logic.
The original problem is roughly #2 xx 14#, so you want the answer to be around 28, not 2 or 280.

That means that you should locate the decimal point to make the answer be about 30, not 3 or 300.