
Answers 1: 999
The biggest possible answer for a 3 digit number is 999, which can be achieved by moving the two matches in the second and third digit as shown in the image below. However why should we limit ourselves to 3 digit number?

Answer 2: 51181
If we move the top and bottom matches from the middle zero, it will create two "ones". We can move the two matches at the back to create another "one", and thus creating the number 51181. Is this the biggest? Actually there are even bigger number

Answer 3: 81151
We can move the top and bottom matches from the middle zero to the front...

and if we flip the number upside down, we have 81151

Answer 4: 5 to the power of 118
Since we are thinking out of the box, lets get more creative. We can take the two matches and form the (^) power sign, which is 5 to the power of 118

How big is 5 to the power of 118? We asked Siri and this is what it said.

Answer 5: Infinity
We can move the match in the middle of the number 8 and make it a divide sign. That will be 50 / 0 and anything divided by zero is equal to infinity.
