### Brain Teasers

# Red Stones

Series
Series teasers are where you try to complete the sequence of a series of letters, numbers or objects.Series

On the way to the treasure halls of Mount Tangbit, Duraz and his faithful hound Lur must cross a river of boiling mud. There are numbered stepping stones in the river, but the guardians of the treasure have put up a warning sign:

Traveler, beware!

Follow the number pattern of the red stones or you will sink!

Duraz can see that the first three stones are painted red and numbered 8, 16, and 31, but the rest of the stones are unpainted! They are scattered through the mud and have these numbers:

7, 17, 35, 48, 60, 61, 64, 93, 117, 120, 128, 197, 230, 234, 310, 320, 338, 410, 455, 560, 640, 661, 667, 751, 794, 800, 904, 960

To cross the river, Duraz and Lur must step on five more stones after the first three. But first, Duraz must figure out the number pattern.

Which numbers should Duraz and Lur step on?

Traveler, beware!

Follow the number pattern of the red stones or you will sink!

Duraz can see that the first three stones are painted red and numbered 8, 16, and 31, but the rest of the stones are unpainted! They are scattered through the mud and have these numbers:

7, 17, 35, 48, 60, 61, 64, 93, 117, 120, 128, 197, 230, 234, 310, 320, 338, 410, 455, 560, 640, 661, 667, 751, 794, 800, 904, 960

To cross the river, Duraz and Lur must step on five more stones after the first three. But first, Duraz must figure out the number pattern.

Which numbers should Duraz and Lur step on?

### Answer

Duraz and Lur must step on stones 8, 16, 31, 60, 117, 230, 455, and 904 to safely cross the river.The pattern: Each number (after the first) is twice the previous number minus another number that increases in succession from 0 to 6.

8

16 = (8 x 2) - 0

31 = (16 x 2) - 1

60 = (31 x 2) - 2

117 = (60 x 2) - 3

230 = (117 x 2) - 4

455 = (230 x 2) - 5

904 = (455 x 2) - 6

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