
Seven and
Thirteen
Thanks Bob K Find
a calculator and a friend.
Ask a friend to select a threedigit number and enter it twice into the calculator. Example : 345345 Ask your friend to divide this number by 11. Example : 345345 / 11 = 31395 Now ask you friend to divide the result by 13. Example : 31395 / 13 = 2415 Ask your friend to divide this answer by the original threedigit number. Example : 2415 / 345 = 7 Now magically tell your friend that the answer is 7 To change the final answer to 13, tell your friend to divide by 7 in step 3. Example : 31395 / 7 = 4485 4485 / 345 = 13 Why this happens : Entering a threedigit number twice (345345) is equivalent to multiplying it by 1001. (345 x 1001 = 345,345). Since 1001 = 7 x 11 x 13, the sixdigit number will be divisible by 7, 11, 13.
