#math trivia #77 solution

Burt Kaliski Jr. (@modulomathy)
3/17/12 2:12 PM
#math trivia for #March17: #77 is a product of two consecutive primes — fourth such product this year. How many more are there in 2012?

There can’t be that many more, because we’re already up to 7*11, and the square root of 366 — the largest day-number this leap year — is only slightly more than 19. The remaining primes to consider are thus 13, 17, and 19, so there are three more appropriate products: 143, 221, and 323.

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