[Python 3 Solution: built-in try-except]

Type of given 's' is a string.

To convert 's' to number, not string, we use int() or float().

For example,

(1) If s is '5' (type: string), we can try: s=int(s) ==> s is 5 (type: int).

(2) If s is '0.5'(type: string), we can try: s=float(s) ==> s is 0.5(type: float).

(3) If s is '5'(type:string), we can also try: s=float(s)==> s is 5.0 (type: float)

but, if s is 'abc' or 'smdkfsd10', s is not a number. Therefore, int() or float() would not work.

We can apply these principles to solve this problem.

```
class Solution:
def isNumber(self, s):
self.s=s
try:
float(s)
return True
except:
return False
```