It's not hard. If you know the radius of the observable universe and the radius of a hydrogen atom you can just use the metric system and figure it out.
Radius of hydrogen atom: 53 pm... radius of observable universe: 4.40870040022e+26 m
pm is 10^-12 m... so converting all that with 5.3x10^-11 4.40870040022x 10^26 gives you... 2.33x10^38
I switched it all to radius instead of circumference because it's just easier. The circumference is still going to be just 2piR, so you'd get like 1.46x10^39
39 < 40.
Radius of hydrogen atom: 53 pm... radius of observable universe: 4.40870040022e+26 m
pm is 10^-12 m... so converting all that with 5.3x10^-11 4.40870040022x 10^26 gives you... 2.33x10^38
I switched it all to radius instead of circumference because it's just easier. The circumference is still going to be just 2piR, so you'd get like 1.46x10^39
39 < 40.