Soulver: For all your random calculations
I often find myself doing random calculations and I used to do so part manually and part using Alfred's calculator until Alistair pointed me at Soulver, a desktop/iPhone/iPad app, which is even better.
I thought I'd write some examples of calculations I use it for, partly so I'll remember the syntax in future!
Calculating how much memory Neo4j memory mapping will take up
800 mb + 2660mb + 6600mb + 9500mb + 40mb in GB = 19.6 GB
How long would it take to cover 20,000 km at 100 km / day?
20,000 km / 100 km/day in months = 6.57097681677241832481 months
How long did an import of some data using the Neo4j shell take?
4550855 ms in minutes = 75.84758333333333333333 minutes
Bit shift 1 by 32 places
1 << 32 = 4,294,967,296
Translating into easier to digest units
32381KB / second in MB per minute = 1,942.86 MB/minute 500,000 / 3 years in per hour = 19.01324310408685857874 per hour^2
How long would it take to process a chunk of data?
100 GB / (32381KB / second in MB per minute) = 51.47051254336390681778 minutes
Hexadecimal to base 10
0x1111 = 4,369 1 + 16 + 16^2 + 16^3 = 4,369
I'm sure there's much more that you can do that I haven't figured out yet but even for these simple examples it saves me a bunch of time.