For calculations of multiple LNB location on a single dish, I've been using a $3..$4 Sharp EL-501W.
Got my two at Fry's over the years when I've seen them on sale.
Usually around $7..$8, and with a $3..$4 rebate.
Does a fine job.
But right now, Radio Shack is flushing their house brand 65-115 Scientific Calculator.
It's 10 digits, 241 functions, and has a two-line LCD display.
Top line is for the equation, and bottom line is for the answer.
Now, if it just had the tactile keyboard of an HP, it'd be a $100 calculator! - :up
The link above is the PDF, with a picture of the unit.
They're hanging on a peg in the
discontinued section.
Last week they were about $4.47, and last night they were down to $3.67.
Whether for yourself, or for a stocking stuffer (or if you don't plan that far ahead: birthday gift), they are a real winner!.
I bought two last night, and will look for two more today.
You'll be lucky to find one at a store, so shop now or forget it!
And no, they're not necessary for the LNB calculations.
Anything that'll do sin is fine. Even Windows desktop calculator.