text: what is the sum of all positive divisors of 960 excluding 1 and itself ? this is a question i encountered in a college entrance exam. i was stumped ... it took too long ot solve so i had to leave it blank... help? any math wizzes out there? answer a) 2087  first factor 960 = 3*5*(2^6)  set of divisors excluding 1 and 960 =  powers of 2 = 2,4,8,16,32,64  3 and (powers of 2)x3 = 3,6,12,24,48,96,192  5 and (powers of 2)x5 = 5,10,20,40,80,160,320  3x5 and (powers of 2)x15 = 15,30,60,120,240,480,  sum of all = 2087