seconds = 1e9
minutes = seconds / 60
hours = minutes /60
days = hours / 24
years = days/365.25

#Note that "f-string" formatting is used for nice output
#see page 11 of the book:

print(f'One billion seconds is {years:.2f} years')

"""
Terminal> python seconds2years.py 
One billion seconds is 31.69 years
"""