__,__,__,48,100,180, 294,448,648,__,__,__,.......Find the three numbers before and after given numbers in the series.

(In reply to got it by ben powell)

Yeah, I got that too. What I did was take the difference between the known numbers:

48,100,180,294,448,648

And the the difference between them:

52,80,114,154,200

And then the difference between them:

28,34,40,46

And finally the difference between them:

6,6,6

Now, subtract 6 from 28 in the series 28,34,40,....., to get 22, and subtract 6 from that to get 16, and again to get 10. Subtract the 22 from 52 to get 30, subtract the 30 from 48 to get 18. From 30 subtract 16 to get 14, subtract 14 from 18 to get 4. Subtract 10 from 14 to get 4, subtract 4 from 4 to get 0.

The series now goes:

0,4,18,48,100,180,294,448,648,.......

Now do the same from the other side to get:

46+6=52+6=58+6=64

200+52=252+58=310+64=374

648+252=900+310=1210+374=1584                                 

Now for the series we have:

0,4,18,48,100,180,294,448,648,900,1210,1584

Sorry about the lengthy work.

Posted by Justin on 2005-05-13 22:19:56