# How would i do this work out?

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• Sep 13th 2009, 08:48 AM
Math Noob
How would i do this work out?
I need the break down on how to get the answer please.

8 21/22+3/4-5/12=?

The eight is a mix number with twenty one and twenty two
• Sep 13th 2009, 08:53 AM
VonNemo19
Quote:

Originally Posted by Math Noob
I need the break down on how to get the answer please.

8 21/22+3/4-5/12=?

The eight is a mix number with twenty one and twenty two

Im not sure what the 8 is doing there, but let's pretend that it isnt because the idea is the same.

You need to find a common denominator here...

Do you know how?
• Sep 13th 2009, 08:56 AM
Math Noob
the eight is the whole number of 8 21/22

you have to multiply 22 by 8 and then add the 21 correct?

i got that part figured out now what's next? find the common denominator of each fraction?
• Sep 13th 2009, 08:58 AM
e^(i*pi)
Quote:

Originally Posted by Math Noob
I need the break down on how to get the answer please.

8 21/22+3/4-5/12=?

The eight is a mix number with twenty one and twenty two

$\displaystyle 8\frac{21}{22} + \frac{3}{4} - \frac{5}{12}$

Find the LCM of 22, 4 and 12 which is 132 also that 8 can also be written as $\displaystyle \frac{8 \times 22}{22}$
• Sep 13th 2009, 08:58 AM
VonNemo19
Quote:

Originally Posted by Math Noob
the eight is the whole number of 8 21/22

you have to multiply 22 by 8 and then add the 21 correct?

Correct! Sorry that I didn't notice that, by the way. So we will have...

$\displaystyle \frac{176}{22}$

So, now what should we do? The common denominator, right.
• Sep 13th 2009, 09:00 AM
Math Noob
how did you find the common denominator so fast?
• Sep 13th 2009, 09:02 AM
e^(i*pi)
Quote:

Originally Posted by Math Noob
how did you find the common denominator so fast?

Using prime factors.

22 = 2 x 11
12 = 2 x 2 x 3

Multiply any unique prime factors: 2 x 2 x 3 from 12 and 11 from 22:

$\displaystyle 2 \times 2 \times 3 \times 11 = 132$
• Sep 13th 2009, 09:03 AM
VonNemo19
Quote:

Originally Posted by Math Noob
how did you find the common denominator so fast?

I will stand down now.
• Sep 13th 2009, 09:08 AM
Math Noob
lol im still trying to figure it out
• Sep 13th 2009, 09:11 AM
Math Noob
the answer is 9 19/66
• Sep 13th 2009, 09:12 AM
e^(i*pi)
Quote:

Originally Posted by Math Noob
lol im still trying to figure it out

$\displaystyle \frac{197}{22} + \frac{3}{4} - \frac{5}{12}$

As this does not ask for the LCM you don't need to use it - you can cross multiply if you wish

I don't see why you don't number crunch it?
• Sep 13th 2009, 09:17 AM
Math Noob
because i am a noob, and would love to know how to number crunch
• Sep 13th 2009, 09:19 AM
e^(i*pi)
By using a calculator and putting in the numbers

$\displaystyle \frac{197}{22} + \frac{9}{12} - \frac{5}{12}$

LCM is 132

$\displaystyle (\frac{197}{22} \times \frac{6}{6}) + (\frac{9}{12} \times \frac{11}{11}) - (\frac{5}{12} \times \frac{11}{11})$

$\displaystyle = \frac{1182}{132} + \frac{99}{132} - \frac{55}{132}$

$\displaystyle = \frac{1182+99-55}{132}$

which should give the answer
• Sep 13th 2009, 09:21 AM
Math Noob
I have a ti-84 plus i just purchased, I'm trying to figure out how to use it. (Lipssealed)
• Sep 13th 2009, 09:23 AM
e^(i*pi)
I edited my above post to include the answer :)
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