The birthday "paradox" is actually not a paradox. It means that in a group with more than 23 people, the probability that at least two people will have a birthday on the same day is about 0.5. Because this theoretical probability does not match people's intuition, it is called a "paradox".

We can verify it with a simple applet:

```
import random
def birth_paradox(n):
dic={}
for i in range(n):
m=random.randint(1,12)
if m in [1,3,5,7,8,10,12]:
d=random.randint(1,31)
elif m in [2]:
d=random.randint(1,28)
else:
d=random.randint(1,30)
dic[i]=m,d
if len(set(list(dic.values())))<n:
return True
else:
return False
t=0
for i in range(1000):
if birth_paradox(23):
t+=1
print(t/1000)
```

The results are as follows:

Due to the introduction of random numbers, the result of each run is slightly different ~