Answer:
To sum consecutive numbers we use the formula:
n * (n+1) / 2
1 through 55 = (55 * 56) / 2 = 1,540
1 through 9 = (9 * 10) / 2 = 45
10 through 55 = 1,540 -45 = 1,495
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EDITED
Gee, it seems I added ALL numbers from 10 through 55
ALL ODD numbers from 10 through 55 sum to
759
Explanation: