B2公式:
=IF(LEFT(A2,1)="7",6&A2,IF(LEFT(A2,1)="2",8&A2,IF(LEFT(A2,1)="3",8&A2,IF(LEFT(A2,1)="5",8&A2,IF(LEFT(A2,1)="6",8&A2,"原号码错误")))))
下拉即可
=IF(LEFT(A1,1)="7",6&A1,(IF(OR(LEFT(A1,1)={"2","3","5","6"}),8&A1,"原号码错误")))
=IF(MID(A2,1,1)="7","6"&A2,IF(OR((MID(A2,1,1)="2"),(MID(A2,1,1)="3"),(MID(A2,1,1)="6"),(MID(A2,1,1)="5")),"8"&A2,"原号码错误"))