Thread: (URGENT) How to divide and multiply with decimals.

I just need to know the basic rules on how to multiply and divide decimal numbers....Please help! I need this before tommorow so ASAP would be much appreciated.

Originally Posted by Kitty_Kat

I just need to know the basic rules on how to multiply and divide decimal numbers....Please help! I need this before tommorow so ASAP would be much appreciated.

If you're stuck you can always change 1.01 into (101)/(100)

There are some tips and tricks if you want to know them...

So, 1.01 x 2.01 would be 101 x 201? But, if so where would the decimal go in the answer?

Originally Posted by Kitty_Kat

So, 1.01 x 2.01 would be 101 x 201? But, if so where would the decimal go in the answer?

NO! 1.01 x 2.01 would be:

Code:

               101   201   101 x 201   20301
1.01 x 2.01 =  --- x --- = --------- = ----- = 2.0301
               100   100   100 x 100   10000

give me a few minutes and I will post what you need to do without turning them into fractions...
(but first I have to get chopper challenge back )

Edit: I was planning to go into detail with some color coding, but I guess topsquark's way of teaching it works (seriously, I was planning on taking like 5 minutes)

Originally Posted by Kitty_Kat

So, 1.01 x 2.01 would be 101 x 201? But, if so where would the decimal go in the answer?

The usual trick is to count the number of decimals in 1.01 and 2.01 (2 + 2 = 4), calculate 101 x 201 = 20301, then shift the decimal point 4 spaces to the left to get 2.0301.

Division is a bit trickier: Let's do 1.01 / 23.1. Here we subtract decimals: 2 - 1 = 1. Now calculate 101/231 = 0.43723 or so. Now shift the decimal 1 place to the left: 0.043723. (If the subtraction gives a negative number, as in 10.1/2.31, shift the decimal to the right.)

-Dan

Thank you very much.

~Cat

Originally Posted by Kitty_Kat

Thank you very much.

~Cat

You are welcome!

-Dan

Another way to do decimal multiplication is this box method