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Old 08-26-2016, 03:23 AM
aceplace57 aceplace57 is offline
Join Date: Oct 2009
Location: CentralArkansas
Posts: 23,390
What makes these two math tricks work?

Cracked has an article on mentalist tricks.

The one guessing a person's age has me stumped. The algorithm they give works.

Age 32

3 (1st digit) x 5 = 15 + 3 = 18 x 2 = 36 + 2 (2nd number in age) = 38

The person says 38 and you tell them they are 32. By subtracting 6. ***applause***

Age 57
5 (1st digit) x 5 = 25 + 3 = 28 x 2 = 56 + 7 (2nd digit) = 63

Minus 6 they are 57. ***applause***

It works with various ages I tried, but how?

This one is even more confusing. I understand you are working backwards from the answer. Page 108 and 9th entry. So you need a arithmetic operation that yields 1089

The random number at the beginning has me puzzled. How can this algorithm work when it must start with a random number picked by the person?

I'm tempted to write a quick program to see if it really works with all 3 digit number (with no duplicate digits) combinations. But I suspect it does. Somehow it yields 1089 every time.

741 reverse it 147
Subtract 741-147= 594 Reverse it 495
594 + 495= 1089. It works

Here is the entire article


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