When I use math in secret, it is problems to figure out an average. If I eat 16 Hersey Kisses today, and I do this every other day for the entire week then I've eaten about 9 pieces of chocolate a day this week. I guess it's not a secret when I use math but I find myself sort of averaging things that I do out like that. If I want to buy a car that won't break down right away, I'll need maybe $8,000-$10,000, so that would be $278 a month that I'd need to save for three years. But there is no way I could make that much money until I get a real job that is not babysitting so I'd find a cheap, broken $2,000 car on Craigslist. That would be $167 a month for a year, and that is much more reasonable.
I don't really think about it that much, but I do this sort of math a lot. I'm not even sure if it has a name, but it helps me plan I guess, or see what I've eaten.

9%

My dad used to love the Tour de France, and he was a really good biker and triathlete. He'd explain to me that the bikers in the Tour de France would bike up hills and mountains with 9% incline sometimes! I understood how steep that was, and the bikers in the race still astound me that they can bike at such steep paces. He also explained to me that the steepest parts of the race was set up in mountain stages and they are the most difficult. There are four categories in the mountain stages and some that are beyond the categories that are 7% or more! Category 4 is shorter and easier than Category 3 climbs that are 5 kilometers and have a grade of 5%. Category 2 climbs are the same length or longer with an 8% grade while Category 1 climbs last 20 kilometers 6 percent grade. Beyond category climbs include an altitude difference of at least 1,000 meters and have an average grade of at least 7%.
We have some 9% inclines here in Albuquerque that are biked frequently such as Tramway to the Sandia Casino. On Saturdays I see people climbing up with their legs pumping, and I see others that coast down the street sometimes going upwards of 35 mph!

I see that a lot of people have responded to the first question about modern math savyiness, so that makes me nervous about responding to the second question about what mathy idea interests me.
I think fractals are super cool, as well as repeating, never ending patterns like that.
I know that fractals aren't super mathy, but technically they are. Fractals are pretty, and it's difficult to imagine that they go on forever and ever! It reminds me of trying to find the smallest/biggest number. If you take one, and divide it by two, it is one half. If you half a half, it's one fourth. If you half one fourth, it's one eighth. If you half one eighth, you get one sixteenth. And it continues to become a smaller and smaller number, just like a fractal. Cool stuff :)

This sort of relates to math in the way that your neighbor was trying to teach you and help you, but at first you didn't want or didn't care for the extra tips. But after a few days or weeks, you decided (consciously or subconsciously) to take her advice, and it would help you out in the long run, because the roses would come back. This is kinda like me and math because last year I started to fall behind, and my teacher told me to come in, come in, come in and we can work on it! When I finally set up a weekly time to work with her, she was considering to move me down to the lower math. However, I came back strong, like the roses, this year and I'm ready to learn :)