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Simple TTK Calculator Manual

A plain and straightforward implementation of a simple desk calculator.

TTK Calculator animation

Features

  • Support of integers and decimals with a precision of up to 15 digits
  • Addition (+), subtraction (-), multiplication (×) and division (÷) of two numbers
  • Short evaluation (e.g. a sequence of button presses consisting of 9 × = will be translated to 9 × 9 =)
  • Result of a calculation can be automatically used as a first operand of the next calculation (e.g. key sequence 9 × 9 = + 9 = will yield 90)
  • Inversion of a sign of the currently displayed number (±)
  • Correction / removal of last digit of the currently displayed number (←)
  • Reset of the calculator (e.g. after an error) is done via (C) button

User Interaction

Calculator can be operated by a mouse (left-click on the desired calculator button) or through a keyboard (see the Key Bindings chapter).

Calculation Errors

There are basically three types of error a user can encounter

  • Overflow errors are reported by "Number too large" message on the display. This means the result of the calculation contains more significant digits, than it can be shown.
  • Underflow errors are reported by "Number too small" message on the display. This means the result of the calculation is a decimal number too small to be represented even by all digits the calculator is capable of showing.
  • Division by zero error is reported through "Division by 0" message on the display.
  • General purpose error reported simply as "Unknown error" is displayed in case of an unexpected error (i.e. most likely unexpected calculator state due to a bug in the program).

The only way to recover from any error is to perform a calculator reset by pressing the C button.

Key Bindings

First column of every table in this chapter represents the key on the calculator's keypad, the second column contains a comma separated list of keys on your computer's keyboard.

Please note that keys on the dedicated numeric part of your keyboard may not work properly or at all.

Digits

Digit Key Bindings
1 1
2 2
3 3
4 4
5 5
6 6
7 7
8 8
9 9
0 0
. ., ,
± S, s

Control Keys

Control Key Key Bindings
C C, c, <Delete>
← <Backspace>, <Left Arrow>
= =, <Enter>

Operators

Operator Key Bindings
+ +
- -
× *
÷ /