# Question #c4d7e

##### 1 Answer

A quick way to solve nuclear half-life problems is by remembering that, esentially, you are dividing whatever amount you have by 2 for every half-life.

So, if you start with, say, **100 g** of a radioactive isotope that has a half-life of 1 million years, you will have

**the first** 1 million years,

**another** 1 million years,

**another** 1 million years,

**another** 1 million years, and so on...

So, for this example, you are left with **1/4th** of the *original sample* after 2 "cycles". Therefore, since, in your case, the element's half-life is 703 million, **2** "cycles" mean

**703 + 703 = 1406 million = 1.4 billion years**.

If the problem would have asked for, say, **1/16th** of the original sample, that would have corresponded to

**4** cycles. Therefore,

**1/16th** of the original sample.