Primes as the building blocks of numbers.
At left: two abacuses (two numbers stacked).
At right two circles with the prime factors. (two circles with prime numbers stacked)
At right edge: all the prime numbers available to the app.
To create a number: Tap on the cells at left. The app shows the number
To add: Drag the tokens from one abacus to the other.
To subtract: Tap the sign key and drag from one abacus to the other.
To multiply: (the numbers must be previously created with the earlier previous steps)
Drag from one prime circle to the other prime circle.
To Divide a number:
Drag the prime numbers outside the prime circle:
Release prime factors to the other prime circle (integer division and multiplication)
Release prime factors between the prime circles (integer division)
Release prime factors in the list of the right edge: (integer division and erase the prime factor)
Scroll and pick a prime number from the list of the right edge:
And release it in the free zone, or in a prime circle (multiplication)
With this program you can add, subtract, multiply and divide (integer division) of any integer of any sign.
(Practically, the app is operative up to 9 digits).
(Currently, the biggest prime number available in this program is 19.874.419)
In the general menu there are 3 options:
Refresh all (erases all the tokens)
Refresh upper chart (Erases all the upper tokens)
Refresh lower chart (Erases all the lower tokens)
And a info:
The upper current available prime number.
(The app calculates new prime numbers each 20 seconds while the app is not used)