Online games often offer "rare item drop, " allowing users to get items on chance.
However, the probability of getting an item is relatively low, you usually need to try many times to get one.

Here is a simulator for such situations, you can estimate how many times you need to try to get one.

This simulator works on your browser, you don't need Excel or macros.

Simulation: trials. Success: . Ratio: %

( trials, win: , ratio: %)

※Simulation will be here.

↑O:Win、x:lose

When you draw a lottery of 1% 100 times, the probability of winning is 63.4%. You may feel 63.4% is low. Mathematics sometimes contradicts our intuition.

The Birthday Paradox is a famous example for this.

Updated: