@ickplant to Lemmy Shitpost • 1 year agoPaniki.postimg.ccimagemessage-square149arrow-up11.32Karrow-down151
arrow-up11.26Karrow-down1imagePaniki.postimg.cc@ickplant to Lemmy Shitpost • 1 year agomessage-square149
minus-squareKaryoplasmalinkfedilink3•1 year agoFor divisibility by 13, take the last number, multiply by 4 and add to the rest. For divisibility by 17, take the last number, multiply by 5 and subtract from the rest. For divisibility by 19, take the last number, multiply by 2 and add to the rest. In fact, you can adapt the method to check for divisibility by any prime number k.
Our plan to find the witch has worked, boys! Get her!
For divisibility by 13, take the last number, multiply by 4 and add to the rest.
For divisibility by 17, take the last number, multiply by 5 and subtract from the rest.
For divisibility by 19, take the last number, multiply by 2 and add to the rest.
In fact, you can adapt the method to check for divisibility by any prime number k.