Question

Find the next two numbers in the series:
1 , 3 , 6 , 10 , 15 , __ , __

• A. 20 and 26
• B. 21 and 27
• C. 21 and 28
• D. 20 and 27

Answer 1

The correct option is C 21 and 28

The differnce between first two numbers is 2.
Difference between 2nd and 3rd numbers is 3.
Difference between 3rd and 4th numbers is 4.
Difference between 4th and 5th numbers is 5.
So, the sixth term should be six greater than 5th term.
Therefore, sixth term = 15 + 6 = 21.
Seventh term should be 7 gretaer than sixth term.
Seventh term = 21 + 7 = 28.
The next two terms in the series are 21 and 28.