Number Series Puzzles - 13

1.  What number should replace the question mark ?

     10,15,40,165,?

A:-  790

       10
       10+5 = 15
       15+25(5*5) = 40
       40+125(25*5) = 165
       165+625(125*5) = 790.

2. What number should replace the question mark ?

    2,6,14,30,62,?,254

A:-  126

       2
       2+4 = 6
       6+8 (4*2) = 14
       14+16(8*2) = 30
       30+32(16*2) = 62
       62+64(32*2) = 126
       126+128(64*2) = 254.

3.  Look at this series : 14,28,20,40,32,64,.... What number should come next ?

A:-  56

       14
       14*2 = 28
       28-8 = 20
       20*2 = 40
       40-8 = 32
       32*2 = 64
       64-8 = 56.

4.  Look at this series : 1.5,2.3,3.1,3.9,.....  What number should come next ?

A:-  4.7

       1.5
       1.5+0.8 = 2.3
       2.3+0.8 = 3.1
       3.1+0.8 = 3.9
       3.9+0.8 = 4.7.