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Old 2020-09-01, 11:43   #4
JeppeSN
 
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"Jeppe"
Jan 2016
Denmark

2428 Posts
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There must be or have been some inconsistence on how the precedence is when the parentheses are not explicit.

If you type (10^79-181)%((10^79-1)/9) you come to the fully factored 79-digit composite number:
http://factordb.com/index.php?id=1100000000900937469

If you type ((10^79-181)%(10^79-1))/9 you come to the 79-digit prime:
http://factordb.com/index.php?id=1100000000902314000

Both these entries are entirely correct.

However, the entry you link:
http://factordb.com/index.php?id=1100000000900935563
seems to be a mix-up of the two interpretations. It has evaluated to "C" (composite). But when you click Show digits, you see the expansion for the 79-digit prime.

I speculate that one piece of code in factordb sees the expression in one way, and another place sees it in the other way, and we have this mix-up. The schizophrenic entry needs to be removed, and (if not fixed already) the operator precedence convention must be consequent.

/JeppeSN
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