why can't my code keep three significant digits

Question

the code
(input):
a = input('please entet a integer :')
s = pow(eval(a),0.5)
print('{:3f}'.format(s))

when I input 36
my code output 6.000000. why dose it have six 0?
it output3.162278 when I input 10.why did my code didn't work.

then I had changed the code, I used the round function, however, it still was a bit comfusing.

the code
(input):
a = input('please enter a integer:')
s = pow(eval(a),0.5)
p = round(s,3)
print(p)

when I input 36, it output 6.0. however, it output 3.162 if I input 10

Answer 1

There should be a point before "3f". Also, it's better if you use int() instead of eval().

a = int(input())
s = pow(a,0.5)
print('{:.3f}'.format(s))