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.
Plz don’t groth on my dieck, that’s just rude.
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?
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
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)
I always thought it’s 31+20