Pop quiz: you flip a fair coin 50 times. What is the probability that it lands on heads at least 25 times?

The number of computations involved in answering that question is staggering. The formulas can cause nightmares.

"Probability Pro" will tell you that the answer is 55.61% instantly.

How about this classic? In a room of 23 people, what is the probability that at least two people share the same birthday? Believe it or not, it's 50.73%. This powerful application will explain why, and it will calculate the probability for any number of people.

How long would it take you to figure out the answers to those questions without "Probability Pro?" How much time do you want to spend checking your homework?

This application features a rich set of tutorials, examples and solvers for the following topics:

- Odds
- Survey Results
- Venn Diagrams
- Bayes' Theorem
- Permutations
- Combinations
- Taking Balls from Urns
- Replacement vs. Non-Replacement
- Independent Events
- Dice
- Roulette
- Lottery
- Poker
- General Card Problems
- Expected Value
- Birthday Problem
- Normal Distributions
- Poisson Distributions

Please note: there are multiple solvers, but there aren't solvers for every topic.

I welcome all comments, questions, and suggestions:

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Please check out my other applications:

ACT Math Prep
Algebra Pro
Calculus Pro
Finite Math Pro
Geometry Pro
Math Pro (six Math apps for the price of two!)
Physics Pro
PreCalculus Pro
SAT Math Prep
Statistics Pro

What's New

Version 4.6

- Formatting enhancements

Ratings and Reviews



Clean, easy to use, informative. To the reviewer that mentioned the permutation solver limitation, this version has a more advanced solver.



Now that I've been using this for a few hours it's one of the best apps that I've found in the App Store! Not only are the examples and tutorials really well explained and clear, but it's also something that I think I will be keeping for a long time and won't just get deleted when I get bored. I hope the developer keeps adding new features to the app… seems like a lot of topics have been added recently.

Much Like


I've had this app for quite a while now and I really like the fact that it is constantly evolving. With a textbook to get new content you have to buy it again but with this the developer keeps on adding new things like Bayes Theorem which was just added. Everything important is already in the app but it's nice to see new things coming each time.


Larry Feldman
12.2 MB
Requires iOS 9.0 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
You must be at least 17 years old to download this app.
Unrestricted Web Access
© 2009 Larry Feldman


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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