Whole Calculator

Calculator constrained in the set of natural numbers. Write numbers and words. Calculator in the set of the natural numbers (ℕ).
And is able to write all the natural numbers with words.

Type the numerical operations and results in words.

Writing numbers :
The app writes correctly from from the one (10^0) until the centillion (10^303).
Numbers converted in words in a text scroller: Sliding text.

Useful to explore cyclic numbers:
142857 * 5 = 714285; 142857 * 6 = 857142; ......

More cyclic numbers:
(10^6 - 1) / 7 = 142857 (6 digits)
(10^16 - 1) / 17 = 0588235294117647 (16 digits)
(10^18 - 1) / 19 = 052631578947368421 (18 digits)
(10^22 - 1) / 23 = 0434782608695652173913 (22 digits)

.....and much more

The numbers or operations appears in the upper screen converted in words.

Meaning of the buttons:
↺ "Undo" (undo the last action)
↻ "Redo" (redo the last undone action)
C "Clear all" (clears all screens and empty the inner list of actions)
÷ "Divide" (adds the character ÷ on the screen)
× "Multiply" (adds the character × on the screen)
- "Minus" (adds the character - on the screen)
+ "Plus" (adds the character + on the screen)
(The same with all the numerical buttons)
= "Equal" (adds the character = on the screen, add this action in the inner list of actions and performs the operation)

Writing numbers:
The program uses the: SHORT SCALE: (British and US)

Thousands separator conforms to: ISO/IEC 80000-1:2009

Useful:
Pre-Kindergarten: Addition, Subtraction, Number sense
Kindergarten: + Whole numbers, Counting, Writing numbers, Place value
Math 1: + Natural numbers
Math 2...: + Big numbers