Simple layout-

• Large buttons which are easy to read and press.
• Color coded to make locating keys easier:
  • Number keys are light green
  • Operator keys are white
  • Trigonometric keys are blue
  • Other functions (log/sqrt, etc.) are yellow
  • Special function keys (delete/last value/=) are red.
• Units can be degrees or radians (shown on right of input line)
• Entry errors are reported in the answer line.
• The input formula line is directly above the keys
• Output precision can be custom set with up to 17 digits.
• Directly above this is the last answer in numeric output
• The remaining space above this is a 'paper tape' style scroll region.
  •  The lines closest to the keys are more recent than the top lines.
  • Left side shows the input formula / right is the answer.
  • Flick left on a line allows deleting the value.
  • Pick any of these lines and-
    • If the formula line is empty then the formula is brought down for editing
    • Else, if the formula is in progress, then the value (as a number) is appended to the current formula line

Allows reviewing of formula-

The formula input allows you to see every detail of what is being calculated-

• As you are entering it to verify the correct keys are being entered
• After evaluation in the paper tape area allowing verification afterward calculating.

Works in all orientation of your iPhone

Pressing the 'i' information button shows the settings.

 'Digits in answer line' - Number of digits (including the decimal point) placed in the line above the formula and on the right edge of the paper tape area.

'Digits in 'last' answer' - number of digits inserted into formula line when either the 'answer' key or selection of paper tape are used.

Color Table- Allows modifying current color scheme of keys to your own preference.