Mathematics
Look at the sequence of numbers on one column of the Ishango bone: 11, 13, 17, 19. What do these numbers have in common? List the next three numbers that fit this pattern.
Answer
The numbers 11, 13, 17 and 19 are all prime numbers (numbers that have exactly two factors — 1 and the number itself).
In fact, they are all the prime numbers between 10 and 20.
Continuing the pattern of prime numbers beyond 20 :
⇒ 23, 29 and 31 are the next three prime numbers.
Hence, the numbers have in common that they are all prime numbers, and the next three numbers in this pattern are 23, 29 and 31.
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