wow. that's all i can say

From the Slog, stranger blog online, this comes from Dan Savage:

Grab a calculator.

1. Key in the first three digits of your phone number (NOT the area code)

2. Multiply by 80

3. Add 1

4. Multiply by 250

5. Add the last 4 digits of your phone number

6. Add the last 4 digits of your phone number again

7. Subtract 250

8. Divide by 2

Recognize the answer?

Can someone explain to me--before I get stoned--how the fuck this works?