2019 number games
 

[url]https://www.theguardian.com/science/2018/dec/31/can-you-solve-it-2019-in-numbers[/url]

[QUOTE="Ed Southall"]2019 is the smallest number that can be written in 6 ways as the sum of the squares of 3 primes:
7² + 11² + 43² = 2019
7² + 17² + 41² = 2019
13² + 13² + 41² = 2019
11² + 23² + 37² = 2019
17² + 19² + 37² = 2019
23² + 23² + 31² = 2019[/QUOTE]

Then, the rather traditional --
[B]Date jam[/B]

1. [B]Using only the digits 2, 0, 1 and 9, create expressions that equal all of the numbers[/B] 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.

[B][SIZE="3"]Happy New Year![/SIZE][/B] :xmastree:

[QUOTE=Batalov;504513]1. [B]Using only the digits 2, 0, 1 and 9, create expressions that equal all of the numbers[/B] 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.

[B][SIZE="3"]Happy New Year![/SIZE][/B] :xmastree:[/QUOTE]

(9+1)*0+2=2

NEXT...

[QUOTE=Batalov;504513][url]https://www.theguardian.com/science/2018/dec/31/can-you-solve-it-2019-in-numbers[/url]



Then, the rather traditional --
[B]Date jam[/B]

1. [B]Using only the digits 2, 0, 1 and 9, create expressions that equal all of the numbers[/B] 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.

[B][SIZE="3"]Happy New Year![/SIZE][/B] :xmastree:[/QUOTE]
[SPOILER]2=2+(0*1*9)
3=2+1+(0*9)
4=(9-1)/2+0
5=(9+1)/2+0
6=9-2-1-0
7=9-2+(1*0)
8=9-1+(2*0)
9=9+(1*2*0)
10=9+1+(2*0)
11=9+2+(1*0)
12=9+2+1+0
16=(9-1)*2+0
17=9*2-1+0
18=9*2+(1*0)
19=9*2+1+0
20=(9+1)*2+0
27=9*(2+1+0)
[/SPOILER]

just a few guesses.

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)
[url]https://www.mersenneforum.org/showthread.php?t=15616[/url]
Interestingly May, 23 is also prime in 2019. Must be a sign? Time to retire again?