累計差額 算總和 (9987)

E2{=SUM(TEXT(D2-A$2:A$6,"0;!0")*(B$2:B$6-N(+B$1:B$5)))

另解{=SUM(TEXT(D2-A$2:A$6,"[<]!0")*(B$2:B$6-N(+B$1:B$5)))

另解{=SUM(FREQUENCY(ROW(INDIRECT("1:"&D2)),A$3:A$6)*B$2:B$6)