+225 Use the formula S = n2 to find the sum of 1 + 3 + 5 + ... +
861 = . (Hint: To find n, add 1 to the last term and divide by 2.)
+26367 Use the formula S = n2 to find the sum of
1 + 3 + 5 + ... + 861 = ?
(Hint: To find n, add 1 to the last term and divide by 2.)
\(\begin{array}{|rcll|} \hline n &=& \frac{861+1}{2} \\ &=& \frac{862}{2} \\ &=& 431 \\ \hline \end{array} \)
\(\begin{array}{rcll} sum &=& n^2 \\ &=& 431^2 \\ &=& 185761 \\ \end{array}\)
\(\begin{array}{rcll} 1\ + 3\ + 5\ + 7\ + \ ... \ + 859\ + 861 &=& 185761 \\ \end{array}\)
