Sjmarf@sh.itjust.works to People Twitter@sh.itjust.works · 1 month agoIt looks so wrongsh.itjust.worksimagemessage-square37fedilinkarrow-up1375arrow-down113
arrow-up1362arrow-down1imageIt looks so wrongsh.itjust.worksSjmarf@sh.itjust.works to People Twitter@sh.itjust.works · 1 month agomessage-square37fedilink
minus-squareElvith Ma'for@feddit.orglinkfedilinkarrow-up13·1 month agoThe digit sum of 51 is 6, which is divisible by three. So 51 is also divisible by three. It’s not even hard to see that it’s not prime.
minus-squaresugar_in_your_tea@sh.itjust.workslinkfedilinkarrow-up11·edit-21 month agoYup, my personal prime check is: Even? Ends in 5? Digits sum to 3? If it fails all three and it’s not an “obvious” prime (<20), then it’s prime enough for me.
The digit sum of 51 is 6, which is divisible by three. So 51 is also divisible by three. It’s not even hard to see that it’s not prime.
Yup, my personal prime check is:
If it fails all three and it’s not an “obvious” prime (<20), then it’s prime enough for me.