When I was young I learned that when you add up all the numbers if that number is a multiple of 3 than the original number is also divisible by 3. So 51, 5+1=6 and 6 divisible by 3 and so must 51.
Grothendieck’s Prime tripped me up in a maths competition in high school. i had manually stored a list of primes in my calculator, and one of the puzzles involved primes and deducing the combination to a lock from certain clues. my list of primes erroneously included 57, which almost made my team fail the level, until i realized my error.
51 has to be the non-prime number that feels the most prime
For me it’s Grothendieck’s prime.
Well, on the surface, it’s just 60-3, so clearly divisible by 3 itself. Now 221, that’s some fuckery.
When I was young I learned that when you add up all the numbers if that number is a multiple of 3 than the original number is also divisible by 3. So 51, 5+1=6 and 6 divisible by 3 and so must 51.
Dammit, it was right in the post, why did that take me so long?
Plz don’t groth on my dieck, that’s just rude.
Grothendieck’s Prime tripped me up in a maths competition in high school. i had manually stored a list of primes in my calculator, and one of the puzzles involved primes and deducing the combination to a lock from certain clues. my list of primes erroneously included 57, which almost made my team fail the level, until i realized my error.
All the magic goes when you understand it’s 30+21
I always thought it’s 31+20
Why? 19 is 15+4 but is still prime?
Because 30 and 21 are both divisible by the same number, 3.
Exactly 3(10+7)