In details

Guessing a Date of Birth


Ask someone to think about the month number of your birth (January 1, February 2, March 3…). Then ask him to:

1) multiply the number by 2
2) add 5 to result
3) multiply by 50
4) add your age to the result

After the person tells you the result, you should subtract 250. The last two numbers of the final result will give the person's age, while the first number (or first numbers) will be the month of birth. With this information, it is easy to determine the year.

For example, for a person who is 20 years old and born in January, we would have the following operations:

1) Multiply 1 (January) by 2 => 1 * 2 = 2
2) Sum 5 => 2 + 5 = 7
3) Multiplies by 50 => 7 * 50 = 350
4) Sum of age => 20 + 350 = 370

Subtract 250 => 370-250 = 120

From 120, the first number reveals the month (January), and the last two (20) is the age of the person. Simply deduct the year according to the date of the demonstration.