How many combinations are there to make the number 80?

Answer 1

Infinitely many.

Start with sums of two numbers:

0 + 80, 1+79, 2 + 78 etc

then

0.1 + 79.9, 0.2 + 79.8, 0.3 + 79.7 etc

then

0.001 + 79.99, 0.02 + 79.98 etc

and so on.

Then you can have sums of 3 numbers.

and of 4 numbers, etc

You can also have Irrational Numbers in any of these sums..

To increase the number of options you can include negative numbers or subtractions:

81 - 1, 82 - 2, etc and so on with decimal fractions and irrationals in pairs, triplets, quartets, etc.

And throw in multiples. An infinite number of pairs, triplets etc.