My step-by-step Study Guide will help direct your studies and ensure that you cover everything that the GRE tests.

- Video Course
- Video Course Overview
- General GRE Info and Strategies - 7 videos (free)
- Quantitative Comparison - 7 videos (free)
- Arithmetic - 42 videos
- Powers and Roots - 43 videos
- Algebra and Equation Solving - 78 videos
- Word Problems - 54 videos
- Geometry - 48 videos
- Integer Properties - 34 videos
- Statistics - 28 videos
- Counting - 27 videos
- Probability - 25 videos
- Data Interpretation - 24 videos
- Analytical Writing - 9 videos (free)
- Sentence Equivalence - 39 videos (free)
- Text Completion - 51 videos
- Reading Comprehension - 16 videos

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

## Comment on

Sum of 4 Unknown Digits## How about we use A=9, C=-1

## Nice idea, but there are no

Nice idea, but there are no negative digits.

There are 10 digits altogether: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9

## To hard to do in a short time

## Agreed! It's a tricky

Agreed! It's a tricky question.

## why cant c=2?

## Once we know that B = 1 and D

Once we know that B = 1 and D = 0, it MUST be the case that C = 9

If it were the case that C = 2, then we must be able to assign different values for A, B, C and D so that the original sum works. Can you do that with C = 2?

Cheers,

Brent

## Hey I didn't get why and how

## The question tells us that a

The question tells us that a 2-digit number PLUS another 2-digit number yields a 3-digit SUM.

Let's examine some examples of when this occurs:

50 + 80 = 130

29 + 72 = 101

99 + 99 = 198

63 + 71 = 134

18 + 85 = 103

Notice that, in all of these cases, the hundreds digit is 1.

In fact, in this situation, the 3-digit number will ALWAYS have hundreds digit 1.

For this reason, we know that B = 1

Does that help?

Cheers,

Brent

## When you say, "In fact, in

## Oops my bad. I changed my

Oops my bad. I changed my response above to have "hundreds" (not unit)

Thanks for the heads up!

## My logic to remember:

The sum of any two 2-digit numbers can never exceed 198, so, the first digit of the sum must be 1.

## That's perfectly logical

That's perfectly logical reasoning!

## Hello brent,

Can you please let me know, where can I find more similar practice questions?

## This isn't a very common

This isn't a very common question type, but I have found a few similar questions to practice:

- https://greprepclub.com/forum/if-a-b-and-c-represent-different-digits-in...

- https://greprepclub.com/forum/gre-quantative-sum-a-b-c-and-d-represent-d...

- https://greprepclub.com/forum/in-the-following-correctly-worked-addition...

Cheers,

Brent

## Hi dear Brent,

Could you please give us more than three questions of this type, at least 10 practice questions?

Thanks a ton

## This question type isn't that

This question type isn't that common. Here's what I could find on GRE Prep Club:

- https://greprepclub.com/forum/in-the-following-correctly-worked-addition...

- https://greprepclub.com/forum/if-a-b-and-c-represent-different-digits-in...

- https://greprepclub.com/forum/in-the-correctly-calculated-subtraction-pr...

- https://greprepclub.com/forum/digit-problem-10496.html

Cheers,

Brent

## Thanks a ton, I appreciate

## Add a comment