# Lesson: Operations with Fractions

## Comment on Operations with Fractions

Interesting

### This AWFUL-LOOKING fraction..

This AWFUL-LOOKING fraction... LOOOOOL!

So right on the money!

### Ha! Awful indeed! (aside:

Ha! Awful indeed! (aside: Omar is referring to 7:14 in the video)

Cheers,
Brent

### Are the official GRE paper

Are the official GRE paper test reinforcement activity questions from an older version paper test or from the version that has significant overlap with the 2 powerprep practice tests?

### I believe that the questions

I believe that the questions in the paper test do not overlap with the PowerPrep practice tests.

### The last 3 links don't go to

The last 3 links don't go to any specific problems. It just takes you to the homepage of themathpage.com

### Thanks for pointing that out!

Thanks for pointing that out!

Looks like TheMathPage.com changed the urls of all its pages.
I've updated all of the links above, and I'll try to get to the rest of the links (throughout this site) this upcoming week.

Cheers and thanks again,
Brent

### Good question. One option is

Good question. One option is to convert both to entire fractions, and then perform the calculations.

Cheers,
Brent

### Hi Brent,

Hi Brent,

When trying to find the common denominator for 1/3 + 1/6, isnt the common number that divides both 3 and 6 are 3?

I mean 3 is a multiple of both 3 and 6 right?

### 3 is the GREATEST COMMON

3 is the GREATEST COMMON DIVISOR of 3 and 6.
When it comes to adding or subtracting fractions, we want to find the LOWEST COMMON DENOMINATOR, which is the same as finding the LEAST COMMON MULTIPLE.

Sum of multiples of 3 are: 3, 6, 9, 12, 15, 18, 21,....
Sum of multiples of 6 are: 6, 12, 18, 24,30,....
(Aside: Notice that 3 is not a multiple of 6)

Among the above multiples, the SMALLEST multiple they have in COMMON is 6.

### When cross simplifying, is it

When cross simplifying, is it ok to only simplify one set, or do you have to do both?
EX: 5/25 * 5/3
You can 5 & 25, but you can't simplify 5 & 3. So if I simplified 5 & 25 without simplifying 5 & 3, would that mess up my answer?

### No, you need not simplify

No, you need not simplify both pairs of values.
For example, 7/12 x 24/13 becomes 7/1 x 2/13 after simplifying.
Likewise, 25/8 x 11/15 becomes 5/8 x 11/3 after simplifying.

### Good morning......i was

Good morning......i was wondering the above is a good list of questions can i if possible shorten it and do just gre offical questions for practise if that is enough or should i do all

like what i mean is focus on gre only questions and if needed go for others on the list....would love to hear ur advice on the approach.....

### In a perfect world, students

In a perfect world, students would answer every question on the site. That's said, I totally recognize that many students have time constraints that make answering every question impossible.

So, an alternative approach is to first answer practice questions in the 130-149 range until you get 3 correct answers in a row.
Then answer questions in the 150-159 range until you get 3 correct answers in a row.
If you just need a score in the 150-159 range, you can stop there.
If you need a score in the 160-170 range, you should also answer questions in the 160-170 range until you get 3 correct answers in a row.

If you have more time, you can change the 3-in-a-row "rule" to 4 in a row or 5 in a row.