How to write 0.038383838 in bar notation?

0.038 (There's a line of top of the number repeatedly infinitely)

Explanation:

Ok, we have to figure out what number is repeating itself.

0.038383838

We can see that 38 keeps repeating itself.

Therefore, in bar notation it would be 0.038 (There's a line of top of the number repeatedly infinitely, so write a line on top of 38)

I hope this helps!