Answer :

9.8 or the full version 9.899494937
AL2006
98 is not a perfect square, so its square root is irrational.  That means that
it can never be written exactly on paper with digits.  Written as a decimal,
it keeps going forever,and never ends.

The beginning is:  9.89949...

Also, don't forget ...
Every number has two square roots ... one positive and one negative.

The other square root of  98  begins  -9.89949...  and keeps going forever.