20181231, 19:40  #1  
"Serge"
Mar 2008
Phi(4,2^7658614+1)/2
3×3,061 Posts 
2019 number games
https://www.theguardian.com/science/...019innumbers
Quote:
Date jam 1. Using only the digits 2, 0, 1 and 9, create expressions that equal all of the numbers from 0 to 12. The expressions can include any of the arithmetical symbols +, –, x, ÷ and √, and brackets. I’ll start you off: 0 x (2 + 1 + 9) = 0 2 – 1 + (0 x 9) = 1 Note: you must use each of the digits 2, 0, 1 and 9 once and only once in each expression. ...and read on. Happy New Year! 

20181231, 20:02  #2  
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
3^{2}·7·71 Posts 
Quote:
NEXT... 

20181231, 20:10  #3  
"Forget I exist"
Jul 2009
Dumbassville
2^{6}×131 Posts 
Quote:
3=2+1+(0*9) 4=(91)/2+0 5=(9+1)/2+0 6=9210 7=92+(1*0) 8=91+(2*0) 9=9+(1*2*0) 10=9+1+(2*0) 11=9+2+(1*0) 12=9+2+1+0 16=(91)*2+0 17=9*21+0 18=9*2+(1*0) 19=9*2+1+0 20=(9+1)*2+0 27=9*(2+1+0) just a few guesses. 

20181231, 20:29  #4 
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
3^{2}×7×71 Posts 
Dates in 2019 that are All Primes
DISCLAIMER: Standard Date format where I work is: YYYYMMDD.
Dates in 2019 that are prime in all regards. That is, all the following are prime numbers. YYYYMMDD YYYY MM DD MMDD 20190523 20190719 20191117 If you include YYYYMM then only the last 2 numbers above qualify. This is the only date for which ONLY YYYYMMDD is prime: 20191027 I retired (for the first time) on a date like this in 2011 (20110523) https://www.mersenneforum.org/showthread.php?t=15616 Interestingly May, 23 is also prime in 2019. Must be a sign? Time to retire again? Last fiddled with by petrw1 on 20181231 at 20:39 
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