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49 looks prime to me. Another commentator says it doesn't count because it's a square number, but square numbers don't really have a particular "look" to me in
by tshaddox 5y ago
49 looks prime to me. Another commentator says it doesn't count because it's a square number, but square numbers don't really have a particular "look" to me in the same way that 2-digit numbers ending in 5 or with digits summing to a multiple of 3 do.
- aidenn0 5y agoYour maths teacher didn't force you to memorize squares then.
- tshaddox 5y agoI did memorize the sequence and still have it memorized, but I have to enumerate them. They don't have a "look" to them.
- crackercrews 5y agoThere's no "look" for me either. But I immediately know that 49 is not prime because I recognize it as the answer to one of the times table math problems that I learned.
- jcims 5y agoBased on my failure at this game, anything times 19 looks prime to me.
- Dylan16807 5y agoWell you only have 4 of those under 100. The "looks prime" rule assumes you check for multiples of 3, so that removes one. All the rest end in an even digit or 5.
- jcims 5y agoyeah once i started doing the trick for 3's the whole thing got boringly easy