A pedantic but maybe-not-entirely-pedantic point: It depends on what you mean by 99%.
If the calculator has a little gremlin in it that rolls a random 100-sided die, and gives you the wrong answer every time it rolls a 1, then you certainly can use it to build a bridge. You just need to do each calculation say 10 or 20 times and take the majority answer :)
If the gremlin is clever, it might remember the wrong answers it gave you, and then it might give them to you again if you ask about the same numbers. In that case you might need to buy 10 or 20 calculators that all have different gremlins in them, but otherwise the process is the same.
Of course if all your gremlins consistently lie for certain inputs, you might need to do a lot of work to sample all over your input space and see exactly what sorts of numbers they don't like. Then you can breed a new generation of gremlins that...
Yea I know, can't really understand why people have such a problem with this. Just ignore the wrong answers and be thankful when it gives you a right answer. Picky bastards.
If the calculator has a little gremlin in it that rolls a random 100-sided die, and gives you the wrong answer every time it rolls a 1, then you certainly can use it to build a bridge. You just need to do each calculation say 10 or 20 times and take the majority answer :)
If the gremlin is clever, it might remember the wrong answers it gave you, and then it might give them to you again if you ask about the same numbers. In that case you might need to buy 10 or 20 calculators that all have different gremlins in them, but otherwise the process is the same.
Of course if all your gremlins consistently lie for certain inputs, you might need to do a lot of work to sample all over your input space and see exactly what sorts of numbers they don't like. Then you can breed a new generation of gremlins that...