enchanteuse? same as "femme fatale"?

a) Well, $10 on $50 for a week is obviously 20% per week.

As simple annual interest: 52 * 20 = 1040%

b) effective = 1.2^52 - 1 = 13104.63... - 1 = 13103.63...%

YES: means $1 accumilates to ~$13,104 over 1 year!

c) if that means he reinvests the interest at same rate, like a week

after the initial $50, he lends $60 and collects $72 ($12 interest):

YES: that's 655,232 bucksCode:week interest worth 0 0 50 1 10 60 2 12 72 ..... 51 91004 546026 52 109206 655232