Brilliant: A Problem Solving and Competition App

Last September, I have posted about MathCounts Trainer, a math competition app for iOS devices. In this post, I am going to introduce to you Brilliant, another math competition app which is both available in iOS and Android devices.


Brilliant is an app created by intended to train users for problem solving, test preparation, and mathematics and science competitions. It has a wide range of problems in terms of difficulty ranging from basic concepts to Olympiad level. It includes problems in Basic Math, Algebra, Geometry, Calculus, SAT, JEE, Physics, Computer Science, and Quantitative Finance.

In Brilliant, you can select the subject that you want to learn and choose the topic or level you want to study. It contains thousands of problems created by a community of mathematicians and scientists. Users of this app can participate in discussions, follow other members, and learn from the community.

Solving Problems by Eliminating Impossible Cases

One of the strategies in solving problems is to divide them into cases and see if you can eliminate some impossible cases. In this post, I will discuss a popular classic problem which I found the solution to be interesting.


If A, B, C, and D are distinct non-zero digits, find their values if ABCD × 4 = DBCA.

If you have not encountered this problem before, you might want to solve it first before reading the solution below.

Finding the Value of A


One of the most obvious hints of the problem is that the value of A is only limited to 1 and 2. Why? Because if A is greater than 2, 4 × will become a 2-digit number. This will make the product of ABCD × 4 a 5-digit number which does not satisfy the problem.  » Read more

The Math Word Problem Series on Number Problems

Below is the Number Word Problem Solving Series among the Math Word Problem Series in Math and Multimedia. In this series, several strategies were discussed on how to solve number problems.

1. How to Solve Number Problems Mentally

2. How to Solve Number Problems Using the Model Method

3. How to Solve Number Problems Using Algebra Part 1

4. How to Solve Number Problems Using Algebra Part 2

5. How to Solve Number Problems Using Algebra Part 3

In the next series, we are going to learn how to solve numbers involving age problems.

If you have questions or comments, please use the comment box below.

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