Identify the Next Domino

Identify the next domino in the following sequence:

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Answer:

m (+5)            >>> r
68 - (5) * 4      >>> 48
r - 48 == 18 - 48 >>> -30

Five Card Trick

A mathematician asks a volunteer to give him five cards drawn from a pack of fifty-two. He hands one card back to the volunteer and arranges the remaining four in some sequence he chooses. He then hands the sequence to a second volunteer and leaves the room. His assistant enters. The assistant asks the second volunteer to read out aloud the sequence handed to him. The assistant ponders a little and correctly announces the identity of the card held by the first volunteer. How could this be done? In general, how large a deck of cards can be handled if n cards are drawn initially?

Solution: Click here for the solution!

X and Y

Two numbers are such that if the first gets 24 from the second they will be in the ratio 2 to 1, but if the second receives 33 from the first, their ratio will be 1 to 5. What are these two numbers?

Answer: 52 and 62

What are the four numbers?

The sums of four numbers, omitting each of the numbers in turn, are 27, 23, 21 and 19. What are the four numbers?

Answer: 3, 7, 9, and 11
7 + 9 + 11 = 27
3 + 9 + 11 = 23
3 + 7 + 11 = 21
3 + 7 + 9 = 19

Replace the question mark!

Which of the boxes should be used to replace the question mark?

Answer: A