Cam you please help me with this code

Question

it says "nil can't be concerned into float"
https://code.sololearn.com/ct17YYbotL33/?ref=app

Answer 1

I'm not good at Ruby, but it works if you change it like this:
if N > 0
b = 1.0
20.times do
b = N/a
a = (a+b)/2
end
puts b

Answer 2

Try assigning b before
Did it worked?