ARC is a scientific calculator which can do basic (+-*/) and high level mathematical operations (trigonometric, statistics, regression). See below for detailed commands.

ARC runs on the popular arduino platform (AVR/ATmega) with 32 kbyte flash memory and 1 kbyte RAM. Due to the 8-bit-processor ARC calculates only 5 to 6 digits exactly. This should be enough for most calculations (except you are a bookkeeper who wants to add billion-amounts with cent-accuracy).

Buy an arduino, install the arduino software (including appropriate libraries) on your PC and compile/upload "calc.ino" to your arduino. By defining (and compiling) one input and one output channel ARC can be operated by a serial keyboard (terminal software like screen or putty) or a 12 key keyboard (4 rows, 3 columns). Output will be shown on a terminal or a 128x64 OLED-display.

• Basic keys: ENTER, DEL, +, -, *, /, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, EE, CHS, STO, RCL
• Stack operations: SWAP, LASTx, ROT+, ROT-
• Settings: DEG, RAD, FIX, SCI, SCROFF (screen off time in s, 2...200), CLOCK (counts h.ms)
• Mathematics: SQRT, SQR, 1/X, POWER, FACT (!), PI
• Logarithmic, exponential: LN, EXP, LOG, 10x, Py,x, Cy,x
• Trigonometric: SIN, COS, TAN, ASIN, ACOS, ATAN
• Hyperbolic: SINH, COSH, TANH, ASINH, ACOSH, ATANH
• Statistic: CLRSUM, SUM+, SUM-, MEAN/STDDEV (mean value and standard deviation)
• Linear regression: A+BX (interception and slope), ->X,Y (estimation of x and y)
• Other: ANNU (present value for a given interest rate and duration), GAUSS (density and distribution), ->P (convert to polar and ...), ->R (... rectangular coordinates), ->H.MS (convert hours to hours, minutes, seconds ...), ->H (... and back), ->RAD (convert degrees to radians), ->DEG (and back)

http://youtu.be/F3uRQhoFq40

In this video you can see the following calculations:

• Approximating PI with 22/7
• Inserting -3.14159265E-2
• Setting to 6 decimal places (FIX)
• Calculating the mean value and standard deviation of 4, 5 and 6 (including SWAP)
• Convert a rectangular vector (1,1) to polar and back (swap to change arguments)
• Calculating the Gauss normal distribution and density function at 0 (swap to change results)
• Starting a clock at 8:16 (and 50 seconds)