# A sample of U-238 initially contained #1.3x10^18# atoms when the universe was formed 13.8 billion years ago, how many U-238 atoms will it contain today?

##### 1 Answer

Jul 12, 2016

#### Explanation:

We can find the number of atoms remaining from an original sample using the half-life formula:

where

Plugging in our numbers we get:

Checking to see if this makes sense, we are left with about

Therefore our answer does make sense.