This strange and agruably pointless problem has already been answered here .
Also...
(B) 630 (0,1,2,3,5,6,7,8,9)
choose a number say 156
its factors are 1,2,3,4,6,12,13,26,39,52,156
grouped by last digit (1) (2,12,52) (3,13) (4) (6,26,156) (78) (39)
We say the FENDERS (factor enders) of 156 are 1,2,3,4,6,8,9 &that 156 is a 7-fender (it has seven fenders)
A) Show that a number which has 0 & 9 as fenders has at least four more fenders.
B) Find 3 9-fenders less than 1000 with different sets of fenders?
I know 900 is one(0,1,2,3,4,5,6,8,9) & 420 is another (0,1,2,3,4,5,6,7,8) but can't find another?