SOLUTION: How to find the sum of even numbers from 2 to 80?

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Question 1070098: How to find the sum of even numbers from 2 to 80?
Found 2 solutions by josgarithmetic, Alan3354:
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
2 times sum from 1 to 40.

2%281%2B40%29%2840%2F2%29
2%2A%281%2B40%29%2A40%2F2
41%2A40
1640

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
How to find the sum of even numbers from 2 to 80?
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2 to 80 --> 40 even numbers.
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Use pairs:
2 + 80 = 82
4 + 78 = 82
6 + 76 = 82
etc for 20 pairs
20*82 = 1640