Seventeen is prime. The repeating string in the decimal representation of it's reciprocal has 16 digits, one less than 17. Subtracting 17 from 100 leaves 83. Powers of 83 can be added in a certain way to create the same repeating string.
The numbers 31 and 41 are prime numbers. The repeating string for 31 is half as long as one less than 31. The repeating string for 41 is an eighth as long as one less than 41.
Used to do hard core extreme stuff, like teaching math to young people- and easier stuff like pushing one's wheelchair up long and steep mountain roads. Now I sit on the porch outside the house and listen to public radio while I stare at pine trees and lights and shadows.