1x2x3+2x3x4+3x4x5+…+8x9x10

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1x2x3+2x3x4+3x4x5+…+8x9x101x2x3+2x3x4+3x4x5+…+8x9x101x2x3+2x3x4+3x4x5+…+8x9x101×2×3+2×3×4+3×4×5+……+8

1x2x3+2x3x4+3x4x5+…+8x9x10
1x2x3+2x3x4+3x4x5+…+8x9x10

1x2x3+2x3x4+3x4x5+…+8x9x10
1×2×3+2×3×4+3×4×5+……+8×9×10
=(1/4)(1×2×3×4)+(1/4)(2×3×4×5-1×2×3×4)+(1/4)(3×4×5×6-2×3×4×5)+……(1/4)(8×9×10×11-7×8×9×10)
=(1/4)(1×2×3×4+2×3×4×5-1×2×3×4+3×4×5×6-2×3×4×5+……+8×9×10×11-7×8×9×10)
=(1/4)(8×9×10×11)
=2×9×10×11
=1980

6+24+60+120+210+336+504+720=1980

inter i,s
do i=1,8
s=i*(i+1)*(i+2)
end do
write(*,*) 'result=',s

1980