1 / 2 + (1 / 3 + 2 / 3) + (1 / 4 + 2 / 4 + 3 / 4) +. + (1 / 40 + 2 / 40 +... + 38 / 40 + 39 / 40) It can be seen that the number equidistant from the first place in each bracket is added, so the items in brackets can be arranged in reverse order and added Who can help me

The original formula = 1 / 2 + (1 / 3 + 2 / 3) + (1 / 4 + 3 / 4 + 2 / 4) +... + (1 / 40 + 39 / 40 + 2 / 40 + 38 +... + 20 / 40) = 1 / 2 + 1 + (1 + 1 / 2) + 2 + (2 + 1 / 2) +... + (19 + 1 / 2) = (1 + 2 +... + 19) + (1 / 2 + 1 / 2 +... + 1 / 2) = (1 + 19) × 19 △ 2 + 1 / 2 × 20 = 190 + 10

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