after a given number of years, type in the number of years and click on Calculate.. of dating lies in trying to determine how much carbon 14 (the radioactive.Carbon dating is based upon the decay of 14C, a radioactive isotope of carbon with. We can use our our general model for exponential decay to calculate the.More radioactive dating - higher tier only. Carbon dating. The amount of carbon-14 in the atmosphere has not changed in thousands of years. Even though it.