Mystery Sequence
Replace the letters with the correct numbers in this interesting series:
1, 8, 15, 3, a, 19, 9, 18, 10, b, 14, 7, 5, 4, c, 13, 0, 12, 16, d
What value has rounded to the nearest integer?
The answer is 5.
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1 solution
Write down all the numbers from 0 to 19. Start at 1. Jump 7. Repeat. When you get to 19, go back to the start of the list. Once you land on a number in your original list, it gets removed so that it is not used again as you traverse the numbers. You can imagine the list as numbers being around the circumference of a circle as you go round and round. Here is the sequence that is produced as a result:
1, 8, 15, 3, 11, 19, 9, 18,10, 2, 14, 7, 5, 4, 6, 13, 0, 12, 16, 17.
With a = 11 , b = 2 , c = 6 , d = 17