No.but are the calculations correct?

In the explicit sum, 6x occurs 7 times, but in the sigma-expression, it is used only 6 times.900: 1x+2x+3x+4x+5x+6x+6x+6x+6x+6x+6x+6x

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900: S (upper: 5 lower: 1) ix + S (upper:6 lower: 1) 6x where x = 10000

It is not clear what 6x is doing in the sigma-expression and why you have \(\displaystyle \sum_{i=7}^5ix\), where the upper limit is less than the lower one.500: 1x+2x+3x+4x+5x+6x+7x+8x+8x+8x+8x+8x

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500: S (upper: 5 lower: 7) ix + S (upper:5 lower: 1) 6x where x = 10000