math
posted by lesly on .
Find a shortcut for computing the sum: 1+3+5+7++11+13+15+17=?? Explain your shortcut and how you could use this same shortcut to find the sum of all the odd numbers form 45 to 99.

what is the sum of the 1st and last?
what is the sum of 2nd and 2nd last ?
what is the sum of 3rd and 3rd last ?
mmmmhhhh? 
1+17=18
3+15=18
5+13=18
7+11=18
4*18=72
45+99=144
47+97=144
49+95=144
51+93=144
53+91=144
55+89=144
57+87=144
59+85=144
61+83=144
63+81=144
65+79=144
67+77=144
69+75=144
71+73=144
14*144=2016