Number Series Puzzles - 11

1.  What number should replace the question mark ?

     1,8,16,25,?

A:-  35

       1
       1+7 = 8
       8+8 = 16
       16+9 = 25
       25+10 = 35.

2.  Look at this series : 544,509,474,439,.... What number should come next ?

A:-  404

       544
       544-35 = 509
       509-35 = 474
       474-35 = 439
       439-35 = 404.

3.  What number should replace the question mark ?

      5,10,17,26,37,50,?

A:-  65

       5
       5+5 = 10
       10+7 = 17
       17+9 = 26
       26+11 = 37
       37+13 = 50
       50+15 = 65.

4. Look at this series : 80,10,70,15,60,..... What number should come next ?

A:-  20

       80
       10
       80-10 = 70
       10+5 = 15
       70-10 = 60
       15+5 = 20.