Calculate the sum of first 19 natural numbers.
Select:
A) 190	B) 120	C) 150	D) 199	E) 110

Rationale: solution we know that ( 1 + 2 + 3 + . . . . . + 19 ) = n ( n + 1 ) / 2 therefore ( 1 + 2 + 3 + . . . . + 19 ) = ( 19 × 20 / 2 ) = 190 . answer a
Answer: A