aquilae wrote:
How do you solve the puzzles with only subtraction? This seems to be about the only puzzle type I am often incapable of solving.
Hi, aquilae, I would suggest the use of the parity rule, which is specially useful, for this type of puzzle. Knowing if a determined cell must be even or odd, or if the sum of two contiguous or not contiguous cells in the same line must also be even or odd is many times a big step.
With respect to the problem of the images dissapearing or not accesible from "ImageShack" (mentioned by bram and Patrick) I must say that this is very discouraging, in my case I have not received any mail from them in this respect, anyway I always thought that the old images were going to be kept "for always", regardless of requiring, in a determined moment, some tax "for the future". My last images were sent via imgur.com following the Patrick's advise anyway.
Not sure how many of them could be recovered in the coming weeks, in my case I think I have some in my PC, but it is tedious to resend them all, for instance: I wrote the post "Step by step solution for a 7x7 subtractions only" in English and in Spanish (in both Forums).
I am not any expert in computer programming, but another suggestion (though the best solution is the one mentioned by Patrick, that is, storing himself everything): Unfortunately our Forum requires that you upload the images to some web page or "virtual" storage where everyone goes later to download every image, I would have rather preferred the possibility of uploading everything in a simple .pdf document, for instance, easy to prepare and send, and donwload and save by the puzzlers; the option "Print view from Forum" is an alternative for puzzlers to keep it for future reading, etc., but it prints the full thread and not only the specific post, ... .