When compounded at seven per cent per annum an amount will double in ten years, i think that is also true? .... this is used in computing interest, but also in population growth - parts of our estado not too far from our 'other house' have had a few years ago a natural increase of seven per cent annually .... scarey stuff, young women of twenty-two with six kids were not uncommon, and are still not rare enough
The 'rule of seven' i associate most with the salesman's belief ... this is why we get hammered so much with garbage advertising, the sad fact is that people's resistance can be broken down by repeated assault on their intelligence ..... email has become useless as a medium of communication, there is so much spam in it now that anything of value gets lost
[edit] - sorry, wandered a bit off topic there ... been enjoying your posts, you guys ... cheers