An open-source calculator program, available as a perl script, that enables calculation of large numbers that would overflow `GNU bc`, bignum libraries or any mortal handheld calculator. It was originally a PalmPilot program, and you might still find that version if you look hard. It has also been made into a JavaScript version, use Google and search for "HyperCalc" on site "edu.hk"

It represents numbers in floating-point notation with as many as 300 digits, and when the exponent gets too large, it converts the number to a logarithm.

Here is an example of using Hypercalc to compute the factorial of the number of atoms in the author's body:

```bash\$ hypercalc

Go ahead -- just TRY to make me overflow!

_ _
|_| . . ._   _  ._  _ ._  |  _
| | | | | ) (-` |  (  ,-| | (
~ ~ _7  |~   ~' ~   ~ `~` ~  ~

Enter expressions, or type 'help' for help.

C1 = weight = 102

R1: weight = 102

C2 = atoms = weight x 10^26

R2: atoms = 1.02 x 10 ^ 28

C3 = r2 !

R3: 10 ^ ( 2.8125791803656 x 10 ^ 29 )

C4 = 27^weight^atoms

R4: 10 ^ ( 10 ^ ( 2.0487721751971 x 10 ^ 28 ) )

C5 = 27^42^weight^atoms

R5: 3 PT ( 2.0487721751971 x 10 ^ 28 )

C6 =
```

In the last result, "3 PT" means "3 powers of 10". It is an interesting exercise to convince yourself why R5 appears to be the same as 10 to the power of R4.
To find the Hypercalc source code on the web, use a search engine like Google and search for the string "pt_addpos", or "hypercalc interpreted calculator overflow".