# birthday problem: calculating

There's a famous probability exercise called the birthday problem. It's an interesting problem for sure, but typically it is calculating the wrong thing. In this series of videos we'll explore what this means.

**Notes**

Here's the code that we're running in the notebook.

```
import numpy as np
import matplotlib.pylab as plt
def calculate(room = 20):
return 1 - np.prod((365 - np.arange(room))/365)
plt.plot([calculate(r) for r in range(1, 35)], label="calculated")
```

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