# math

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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.

• math -

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?

• math -

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

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