I am a singer who has always sung and I have a strange ability which seems to relate to numbers and measurements. I can select a piece of trimming for a piece of sewing I'm working on, without measuring either, and it will exactly fit the article. I might add that I dislike sewing and rarely do it, so I doubt if it's practice. Mostly I just glance at both without thinking, in fact it works better if I'm distracted. I am also restoring a wooland area and I can select a box of trees (the size of the boxes varies),handfuls of treeguards and handfuls of stakes to use with the guards (3 per guard)and the numbers of all three objects will match more often than not. And I often deal in hundreds. I don't store the guards and stakes in groups of any particular number - mostly they have been used before, and the numbers are random. These are just 2 examples but it happens all the time with most things I do. I have no particular ability with formal arithmetic and have'nt studied maths.