Find the sum of the 6 smallest consecutive natural numbers

1 , 2 , 3 , 4 , 5 , 6 are the smallest consecutive natural numbers.

Thus :

1 + 2 + 3 + 4 + 5 + 6 =

3 + 3 + 4 + 5 + 6 =

6 + 4 + 5 + 6 =

10 + 5 + 6 =

15 + 6 =

21

yes because there is exactly one y value for every x value

for function there can't be more than one value for every x value