Question

34. the best way to find the sum of 1,2,3,4,5,6,7,8 and 9 is
(A) (1 x 9) + 9/2
(B) (1 + 9) x 9
(C) (1 + 9) x 9/2
(D) 1 + (9 x 9/2)
35. the best way to find the sum of 1,2,3, - - - 90 is
(A) (1 + 90) x 90/2
(B) 1 x 90 + 90/2
(C) 1 + (90 x 90/2)
(D) (1 + 90) x 90
pls answer I will mark u as Brainliest

Answer 1

Answer:

34.the formula is::n×(n+1) /2

here 9 numbers are existed.

so the sum of these consecutive 9 numbers is 9×(9+1) /2.

35.this is also similar question:

here 90 consecutive numbers are existed,

so the sum is 90×(90+1) /2