Memorizing digits using a 500 images system

Someone on FB asked me how I memorize numbers using only 500 images. Since I feel my answer is valuable, I have decided to post my answer here and give FB the link.

At each locus, I place on my right any number 500 to 999 for which I have major images. When the number is lower, I mentally add 500 to it and post it on the left. I'm doing a bit more to ensure that I remember correctly the one out of seven possibilities at each location, ( I post 3 images per locus) but as I get better with this method, I find that this isn't necessary.