Answer:
Step-by-step explanation:
If the series has a fixed gap between entities (terms).
Add the first and the last values and multiplied by the half of number of terms
For example
[tex]\frac{n}{2} (N_{1}+ N_{n})[/tex]
2,4,6,8,10 = 5/2 (2 + 10) =30
2+4+6+8+10 =30
