How can you get 45 adding?

Answer 1

There are infinitely many ways.

1+44, 2+43, 3+42, ...

Then there are

0.1+44.9, 0.2+44.8, 0.3+44.7, ... , 1.1+43.9, 1.2+43.8, ...

and

0.01+44.99, 0.02+44.98, 0.03+44.97, ...

And, just when you thought you had finished,

1+1+43, 1+2+42, 1+3+41 and other triplets, quartets, quins, ...