New: Touch decimals: free Android app: Part II
Main components of Touch Decimals:
The main board with two charts of identic number of inner rectangles.
Each chart with:
A number with dot that represents each one of the two numbers.
A button to change the sign of all the inner components of each chart.
A row of a variable number of rectangles named: “Places”
A variable number of big dots (with numbers inside), named: “Tokens”.
In the “settings” button or option button: the way to refresh the charts.
A place is a rectangle, and a rectangle has 4 borders:
The top and bottom border may limit another equivalent place, or an abyss where can fall tokens, and become lost forever.
A token is free to cross any of those boundaries under its responsibility.
The left border is impenetrable:
Only it is authorized by the passage of a token if it gets the support of 10 tokens of the same type.
When the 10 tokens have crossed the left border, become one token
The right border:
Right border can be crossed freely
If a token cross the right boundary, it becomes 10 tokens of the same type in the next place.
The maximum reccomended number of tokens into each place is: nine.
A token can be either positive or negative
A positive token is born with the tap of a finger on the screen
A pair of positive-negative tokens is born with a tap of two fingers on the screen
A token disappears if it crosses the top or bottom border.
Positive and negative tokens have the same behavior:
A token can cross at will the intermediate horizontal border
When a token crosses the border on the right, it becomes 10 tokens.
A token need 9 companions from the old place to cross the border to the left.
Positive and negative tokens may be in the same place.
But if two tokens of different signs meet, they cancel each other.
Touch decimals,Place value ±
This is how the tokens live in their places in "Touch decimals, Place value ±"
The behavior of places and tokens of this app describes the behavior of the numbers in the decimal system.
All in this text: charts (twins), places and tokens also describes the internal structure of the app and his internal java classes: