Tchisla: Number Puzzle [iPhone]

Tchisla is a really absorbing number puzzle from the creators of Euclidea. Explore the magic world of numbers and train your mental arithmetic skills. All you need is to represent numbers as arithmetical expressions using only one of the digits from 1 to 9. This can be done in various ways. You gain more points if your solution uses fewer digits and sometimes your way to the optimal solution looks like an exciting quest.

You can use standard arithmetic operations +, -, *, /, and brackets, extract square roots (√), raise to a power (^), and apply factorials (!). The factorial (n!) is the product of all positive integers less than or equal to n.

For example:

96 = 99 - √9
96 = 4 * 4!
96 = 2 * 2 * (22 + 2)
96 = 111 - (1 + 1)^(1 + 1 + 1 + 1) + 1
2048 = ((5 + 5) / 5) ^ (55 / 5)

The idea is easy but it can be very hard to find the shortest solution. Try to solve 64#4 using 2 digits or 71#7 with just 3 digits. Here 64#4 means that you need to express 64 using only 4. When the solution is found, you can stop for a moment to take a look at the received formula and to enjoy and appreciate all the beauty of the mathematics.

*** More than just a calculator ***
Tchisla looks like an ordinary calculator but it is designed to help you in your fight with the problem. It proposes you autocomplete variants that can lead you to the goal. You choose the way and the app calculates and performs all the menial job for you. In short time you suddenly discover that you know a lot of numbers and their properties: factorials, squares, cubes, prime numbers, roots and others. Tchisla imperceptibly helps you to improve your calculating skills.

*** Game modes ***
* The Practice mode consists of a short tutorial and the most interesting problems to solve with numbers from 1 to 100.

* 2016 is the number of the year and one more mode. You need to express it with each digit from 1 to 9. Can you reproduce the world record? It uses totally 48 digits.

* In the Gallery, you can find a table of numbers and the count of digits used in solutions. You can solve new problems here and find solutions that can be improved. This will help in future challenges since they can be based on the levels that are already solved.

You can extend the standard Gallery up to 10000 (via in-app purchase). It will help you to track your progress and the current records and to get quick access to any number or solution. The Extended Gallery contains 50 sections with 200 numbers each (1800 exercises).

* The Contest mode is a regular competition between players. A number to be expressed is announced and you have just 24 hours to find the shortest solution for each digit. You win the gold medal if you have used the minimum number of digits. Do not lose your chance to become the first in the rating!

*** Gestures and controls ***
- swipe to the left to erase the expression
- swipe to the right to restore an existing solution
- double tap on the solution to switch between alternative variants
- yellow square with digit count means that nobody has found a shorter solution. Maybe, it is you who will break the record?

*** Why Tchisla ***
"Tchisla" is the Russian word for "numbers". With our app you will find out a lot of dependencies between numbers, discover their secrets, learn a lot of tricks to tame them or even become their friend. Numbers will become not just sets of digits for you.

*** Questions? Comments? ***
Send in your inquiries and stay up-to-date on the latest Tchisla news at http://www.euclidea.xyz/ and http://www.twitter.com/tchisla.