Chris received $1 on his first birthday,$3 on his second birthday,$6 on his third birthday,$10 on his four birthday.How much money will Chris receive on his eighth birthday if the pattern continues?
math - drwls, Monday, May 9, 2011 at 7:54am
1+2+3+4+5+6+7+8 = 36
or, use the formula
n(n+1)/2 = $ 36 (n = 8)