If you start with a 10g chunk of 235 Uranium how much Uranium will be left after 713 million years?

5g will be left

Explanation:

Uranium 235 have a half-life of 700 million * years. This means that the element will decay to half its initial amount by that time. So if I start with 10g chunk of 235 Uranium, after 713 million years, only half of it (5g) will be remaining.

*the exact half life of Uranium 235 is 703,800,000 years.