Ok, so I had a few questions on this test that I'd like some help with.
(60) 21x43x65x87=_____________ answer: 4,851,142--5,361,788
(70) (8!/6!)(7!/5!)(6!/4!)=_________________ answer: 67,032--74,088
(79) 2,6,15,28,55,k,119,... k= __________ answer: 78
Obviously, the first two are estimation problems, I would just like some way to work them a little bit faster. And on 79 I have no idea what type sequence this is, can anyone help me out? Thanks!