Question

5 + 10 + 15 + .... + 100 എത്ര ?

• A. 1000
• B. 1100
• C. 1050
• D. 1200

Answer 1

Answer:

C. 1050

5 + 10 + 15 + .... + 100 = 5(1 + 2 + 3 + ......... + 20) = 5( 20 × 21/2) = 5(210) = 1050 n എണ്ണൽ സംഖ്യകളുടെ തുക =n[n+1]/2