What equals 66?

There are infinitely many possible answers.

Start with integer sums of two numbers:

33+33, 32+34, ... , 1+65, 0+66, -1+67, -2+68 ... all the way to infinity!

Then two number to 1 decimal place (dp):

32.9+33.1, 32.8+33.2, 32.7+33.3 and again, all the way to infinity.

Next, pairs of numbers to 3 dp, 4 dp, 5 dp, ... to infinitely many dp.

Back again, and consider sums of 3 numbers, 4 numbers, 5 numbers, ... , infinitely many numbers.

That takes care of additions. You can next move to multiplication, and then other mathematical operations.