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Find that decade (Posted on 2014-01-06) Difficulty: 2 of 5
There has been only a single instance in the course of American history (1776 AD onwards) wherein there was a decade in which four of the years were prime numbers. Find that decade.

No Solution Yet Submitted by K Sengupta    
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Solution spoiler | Comment 1 of 4

1879 , 1877, 1873, 1871 --were prime years.*


*btw ,exactly twenty years LATER 1891, 1893, 1895, 1897, 1899,  were  ALL composite!!

(it will happen again in 2081, 2083 ,2087, 2089),+
exactly twenty years LATER  2101,2103,2105,2107 &2109  will be ALL composite!!

Edited on January 7, 2014, 8:54 am
  Posted by Ady TZIDON on 2014-01-06 10:18:21

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