
import math

# Define the constants
C_ratio = 0.157  # 14C/14C_0
k = math.log(2) / (1.82 * 10**11)  # in s^-1

# Calculate the time
t = -math.log(C_ratio) / k  # in s
result=t / 10**11  # in 10^11 s
print(result)
