# Lesson: Properties of Real Numbers

## Comment on Properties of Real Numbers

### This seems too basic for the

This seems too basic for the GRE.

### While you might not see any

While you might not see any questions on the test that directly test the concepts in this video, you still need to know those concepts, since they could play a role in a more complex problem. That said, the beauty of a self-paced course is that, if you already know the concepts taught in a certain lesson, you can always skip that lesson. Happy studying!

Fair enough!

### I have a doubt here. The

I have a doubt here. The reinforcement activity questions here- Are they related to real numbers? If yes then should we solve each reinforcement activity after completing that certain lesson or should we solve the reinforcement activity after finishing that whole module?

### The reinforcement activities

The reinforcement activities are (somewhat) related to the video lesson. So, I recommend that you solve them once you watch the video.

### If 2,4,6 and 9 are the digits

If 2,4,6 and 9 are the digits of two 2-digit integers, what is the least possible positive difference between the integers?

### Good question!

Good question!
I'm assuming that each digit may be used only ONCE (otherwise, we could just make both integers the same, like 29 and 29).

The solution requires a bit of logic and a bit of fiddling.

Since we're trying to MINIMIZE the difference, we want to create two 2-digit numbers that are as CLOSE AS POSSIBLE.
So, we should start by making the two TENS digits as close as possible.
We have two options:
Option #1: Use 2 and 4 as tens digits (since they are only 2 apart)
Option #2: Use 4 and 6 as tens digits (since they are only 2 apart as well)

We want to place the remaining integers (6 and 9) in the units positions so that the difference between the 2 integers is minimized.
We get 29 and 46
The difference = 46 - 29 = 17

Now place the remaining integers (2 and 9) in the units positions so that the difference is minimized.
We get 49 and 62
The difference = 62 - 49 = 13

Looks like the least positive difference is 13

Cheers,
Brent

Thank you.
Eke

### In a factory, machine A

In a factory, machine A operates on a cycle of 20 hours of work followed by 4 hours of rest,and machine B operates on a cycle of 40 hours of work followed by 8 hours of rest. Last week, the two machines began their respective cycles at 12 noon on Monday and continued until 12 noon on the following Saturday. On which days during that time period was there a time when both machines were at rest?

in this question the machine is stoping on both wednesday and friday . then why we have concluded it as friday?

The official answer is C and E, which means both machines were at rest (at the same time) on Wednesday and on Friday.
The question asks us to identify ALL days on which both machines were at rest.

Does that help?

Cheers,
Brent

### Hello Brent,

Hello Brent,
I am trying to understand how to follow the book pages that you mentioned from the official guide, when I look for page 116 #3, which is currently a verbal part on my book. I am originally from Brazil, not quite sure where I am getting lost. Thank you in advance.

### I'm happy to help.

I'm happy to help.

In the Study Guide, I reference two different Official Guides for GRE Review:
- The 3rd edition: https://www.amazon.com/Official-Guide-General-Test-Third/dp/1259862410
- The 2nd edition: https://www.amazon.com/Official-Guide-Revised-General-Test/dp/007179123X

Are you referring to the correct edition?

Also note that the GRE test-makers also have other resources that comprise of Quant-only and Verbal-only practice questions.
Those two resources are not referenced in the Study Guide. That is, I don't assign specific questions from those Quant-only and Verbal-only books.

Note: The practice questions are listed in the form page#(question#).
For example, 118(2) refers to question #2 on page 118.
Likewise, 262(13) refers to question #13 on page 262.

Does that help?

Cheers,
Brent

### https://greprepclub.com/forum

https://greprepclub.com/forum/term-after-the-first-term-is-equal-to-the-preceding-term-1828.html