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

48 is the 4th number, 100 the 5th, 180 the sixth,...
Write the rank under the numbers:
48  100  180  294  448   648
 4      5      6     7      8       9
Dividing these two gives:
12    20    30   42    56     72
So it is going up by a number that is always 2 more:
     8      10    12    14   16
Following the above gives as first three numbers
0   4 and  18
The three last ones are:
900  1210  1584

Posted by Hugo on 2005-04-28 19:32:50