how do i solve this equation? exp(ln(0.81)/2 I always get other number than 0.9

I assume this is :

e^[ln (0.81) /  2 ]  .....if so, we have

e^[ (1/2) ln (0.81) ]  =

e^[ ln (0.81)^(1/2) ] =

Remember that  ......  e^[ln a]   = a

(0.81)^(1/2)  =

√[ 0.81]  = 

√ [ 81/100]  =

9/10  =  0.9

Thanks a lot!!!!