What number add up to 123?

Answer 1

There are an infinite number of possible answers:

1 + 122, 2 + 121, 3 + 120 etc

then

1.1 + 121.9, 1.2 + 121.8 etc

and

1.01 + 121.99, 1.02 + 121.98 etc

And then you could include negative numbers:

124 - 1, 125 - 2, etc

and also irrationals: 1+sqrt(2), 122-sqrt(2), etc

etc

And that is only pairwise addition. You could add 3, 4, 5 ... an infinite number of numbers!