The sum of first 45 natural numbers is	Choose one.
A) 1035  B) 1280  C) 2070  D) 2140  E) none

Rationale: solution we know that ( 1 + 2 + 3 + . . . . . + 45 ) = n ( n + 1 ) / 2 therefore ( 1 + 2 + 3 + . . . . + 45 ) = ( 45 × 46 / 2 ) = 1035 . answer a
Answer: A