Have questions about your preparation or an upcoming test? Need help modifying the Study Plan to meet your unique needs? No problem. Just book a Skype meeting with Brent to discuss these and any other questions you may have.

- Video Course
- Video Course Overview
- General GMAT Strategies - 7 videos (free)
- Data Sufficiency - 16 videos (free)
- Arithmetic - 38 videos
- Powers and Roots - 36 videos
- Algebra and Equation Solving - 73 videos
- Word Problems - 48 videos
- Geometry - 42 videos
- Integer Properties - 38 videos
- Statistics - 20 videos
- Counting - 27 videos
- Probability - 23 videos
- Analytical Writing Assessment - 5 videos (free)
- Reading Comprehension - 10 videos (free)
- Critical Reasoning - 38 videos
- Sentence Correction - 70 videos
- Integrated Reasoning - 17 videos

- Study Guide
- Your Instructor
- Office Hours
- Extras
- Prices

## Comment on

Listing and Counting## Hi Brent,

I am sorry but I am confused with the question "can be created using digits 2 and 7 only". Does that mean that the 3 digits # has to contain both 2 and 7?

Thanks a lot!

Kate

## Hi Kate,

Hi Kate,

For that question, we are basically told that the only digits we can choose from are 2's and 7's. It does not mean that every outcome must contain at least one of each digit.

For example, numbers like 222 and 777 meet the give condition.

Cheers,

Brent

## Thank you Brent, I felt like

Kate

## Hi Brent, I am confused with

How many keystrokes are needed to type numbers from 1 to 1000?

A. 2704

B. 2890

C. 2893

D. 3001

E. None of these

My approach:

For 1-9 - 9 strokes

For 10 - 99 - 90*2 strokes

For 100-999 - 999*3 strokes

For 1000 - 4 strokes

Please help me where am I wrong in this?

## The only problem with your

The only problem with your solution is the 3rd step. You have 999 integers from 100 to 999, but there are only 900 integers from 100 to 999.

Here's my full solution: https://gmatclub.com/forum/how-many-keystrokes-are-needed-to-type-number...

Cheers,

Brent

## Hi Bret,

Are these questions, listed below the videos, OG questions?

Im planning to do the OG qs in the end so I was curious.

## Good question, Ari.

Good question, Ari.

The source for each question is listed on the right side of the link.

When I say the source is GMAT Club, then either the original poster didn't note the source or it's an original question that was created by GMAT Club staff.

So, in the above links there are no official questions. That said, I often post unofficial questions if they closely resemble official GMAT questions.

Cheers,

Brent

## Thank you.

That makes sense. Mind Boggling qs nonetheless.

For some reason when I solve the OGs I dont encounter such high levels of difficulties. Are OG qs mostly easy with a few 700 level qs inserted here and there?

## I think you're right. Many

I think you're right. Many non-official questions often push the limit difficulty-wise.

## Add a comment