This is a question that has been asked for eons and has boggled scientists and mathematicians alike for centuries.
How many months is 100 days? Very hard, eh?
No, just joking.
The short answer is THREE (3) MONTHS. Easy peasy.
The longer answer is this:
On average, there are 30 days in a month. All you have to do is to divide 100 by 30, and you'll get 3.33. Thus, the specific answer to the question is that 100 days is equals to THREE POINT THIRTY THREE (3.33) MONTHS.