even numbers are represented by 2n
they are 2n, 2(n+1), 2(n+2) etc until 2(n+29)
we can do a summation of a seqeucne
the nth even number is an=2+2(n-1)
the sum of a sequence of n terms, where the first term is a1 and the last one is an is
[tex] \frac{n(a1+an)}{2} [/tex]
first term is 2
last one is 2+2(30-1)=2+2(29)=60
[tex] \frac{30(2+60)}{2} [/tex]=
[tex] \frac{30(62)}{2} [/tex]=
30*31
the answer is 30*31
