How do you calculate the half life of carbon 14?

A quick way to calculate Half-Life is to use the expression:

##t_((1)/(2))## = ##(0.693)/(lambda)##

Where ##lambda## is the decay constant and has the value of

1.21 x ##10^(-4) yr^(-1)##

So ##t_((1)/(2))=(0.693)/((1 .21).(10^(-4))##

##t_((1)/(2))## = 5.73 x ##10^(3) yr##

Let me know if you would like the derivation of this.