Dealing with probability things in games

The number is irrational so you will never really get the exact number, only an approximation. 

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What can be divided into 25 billion to get 7 billion EXACTLY?

25/7 = 3.5714285714285714

So the answer is

\(3.\dot57142\dot8 \quad billion\:\: times\)

This is a recurring decimal - it can be expressed exactly as a fraction.

So it is NOT an irrational number. It can and is an exact value.

x/25*10^9=7*10^9
x=(7*25)*10^9*10^9
x=175*10^18=175 trillions