The birthday trick

Published on August 26th, 2011
The birthday trick

Here’s a number trick to keep you busy over the weekend. And don’t forget to share it with your friends!

Step 1: Think about the date of your birthday.

Step 2: Multiply the number of your birthday month by 5. (So if you were born in February, it would be 2 and your answer would be 10.)

Step 3: Add 7. (Now it’s 17)

Step 4: Multiply by 4. (Now you’ve got 68)

Step 5: Add 13. (Now you’re left with 81)

Step 6: Multiply by 5. (Your answer is now 405)

Step 7: Add the day of your birthday. (If your birthday is on the 17th for example, add 17. Your answer is now 422)

Step 8: Subtract 205. (You are left with 217)

Does the number you are left with look familiar? It’s your birth date – first the month, then the date!

Do you know the mathematical reason as to why this works? Let us know!

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