## 1. The Famous Mystery Calculator Trick

Ask your friend to choose a number [1-63].

Show them each card here in turn and ask them if their number appears on it.

## You can guess the number by adding the top left corner numbers of each card that has their number.

Can you find the trick?

## The first hint is if you have one more card, your friend can pick a number [1 - 127]

## Can you guess it now?

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## Another hint is 1 appears only on the first of the cards and 63 appears on them all.

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## ... Yes, It is the Binary way of writing the number - each card is the binary digit represented by the top left corner number. (Cards are not in exact order to create the mystery!)

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## 63 = (1 + 4 + 16 + 2 + 8 + 32) 1 1 1 1 1 1 (in all 6 cards)

## 23 = (1 + 4 +16 + 2) so only in first four cards.

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