+33653 Let s = 1 + 4 + 7 + ... + 85
This is an arithmetic series for which the sum is obtained by taking the average of the first and last terms and multiplying by the number of terms. Here there are 29 terms so:
$${\mathtt{s}} = {\frac{{\mathtt{29}}{\mathtt{\,\times\,}}\left({\mathtt{1}}{\mathtt{\,\small\textbf+\,}}{\mathtt{85}}\right)}{{\mathtt{2}}}} \Rightarrow {\mathtt{s}} = {\mathtt{1\,247}}$$
+33653 Let s = 1 + 4 + 7 + ... + 85
This is an arithmetic series for which the sum is obtained by taking the average of the first and last terms and multiplying by the number of terms. Here there are 29 terms so:
$${\mathtt{s}} = {\frac{{\mathtt{29}}{\mathtt{\,\times\,}}\left({\mathtt{1}}{\mathtt{\,\small\textbf+\,}}{\mathtt{85}}\right)}{{\mathtt{2}}}} \Rightarrow {\mathtt{s}} = {\mathtt{1\,247}}$$
