number of terms in the series = number of digits in the sum?

e.g.: 100 + 101 + 102 = 303

Number of terms in series = 3
Number of digits in the sum = 3

Hi,
According to statement(2):
If the set of consecutive integers is {1,2,3,4,5,6}, the n- digit number formed is the number 12345.
If the set is {2,3,4,5,6,7}, the number is 234567.

Frankenstein wrote:Hi,
According to statement(2):
If the set of consecutive integers is {1,2,3,4,5,6}, the n- digit number formed is the number 12345.
If the set is {2,3,4,5,6,7}, the number is 234567.

Ah, formed "by the series", now I get it. Thanks Frankenstein

a for n = 6 there will be 3 even numbers and 3 odd numbers.

sum of 3 odd numbers say 3,5,7 = odd and sum of 3 even numbers = even
thus e+ o = odd. sufficient.

b the sum of the integers = multiple of 9.

hence, for n(n+1) = 4,5 sum is odd.
for , (n-1)n(n+1) = 9*2 = 18 meaning n=6. thus 5+6+7 = 18 = even.

thus not sufficient.

hence A it is.