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The sum of odd. Focus Secret

Spectacular tricks and their clues

Directory / Spectacular tricks and their clues

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Focus Description:

Ask the viewer to calculate the sum of all odd numbers from 1 to 0 in 20 minute (without a calculator). He most likely won't make it. Speak:

- Well, you and the turtle, try again, just live, what is the sum of the odd ones from 0 to 45 inclusive?

Most likely, the viewer will dismiss it, saying that I couldn’t do it up to 20, but here it’s up to 45 (here it’s already possible with a calculator, but again, it’s limited in time so that it doesn’t have time). You easily count the sum of all odd, even multi-digit numbers (only who will check)

Focus secret:

It is necessary to add 1 to the last (given) odd number, divide by 2 and square it.

Example: from 1 to 49 inclusive 49+1=50, 50/2=25, 25*25=625.

If you are asked to count a very large number, then you will still have to use a calculator, but since it is very small, you will do it in 10-15 seconds.

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