1. The problem statement, all variables and given/known data The initial amount of radioactive atoms on a sample of 24Na is 10^10. It's half-life corresponds to 15 hours. Give the amount of 24Na atoms that will disintegrate in 1 day. 2. Relevant equations I started to solve it using the formula N=Initial Amount of Atoms / e^(λxTime/Half-Life) which ended up as: 10^10 / e^(0.693x24/15) It is supposed to give me the amount of atoms that did not disintegrate in 1 day so I can continue with the problem but my biggest issue here is understanding how to take the natural log (e) to get to the result which is said to be 0.33x10^10. Can somedoby please give me easy step by step explanation on the operation above? Please help before I go crazy. I have an exam soon on which I can NOT use a calculator and it's really important. 3. The attempt at a solution Final answer is: Initial amount of atoms - Atoms that did not disintegrate= 0.67x10^10. I just do not know how to get there since I got stuck at the formula above. I don't know what to do with the "e" on it.