Not sure I am doing this right and need help. If Column B is blank Column A should multiply by Column C. If Column B has info B need to multiply by C

Question

Not sure I am doing this right and need help. If Column B is blank Column A should multiply by Column C. If Column B has info B need to multiply by C

=IF([Column B]="IsBlank" AND, ([Column A]=!Blank), then [ColumnC]*[Column A])
IF ([Column B]=!Blank, then [ColumnC]*[Column B])

Answer 1

Try using formula like below for your SharePoint calculated column:

=IF(ISBLANK([Column B]),IF(ISBLANK([Column A]),"",[Column A]*[Column C]),[Column B]*[Column C])

Notes:

1. Sometimes comma(,) does not work in formula (it is based on language or regional settings on your site). So in that case use semicolon(;) instead of comma(,).
2. Use correct display name of your SharePoint columns in above formula.
3. Wrap column names inside [] if your column name has space in it. For example: [My Column Name].

Answer 2

You could use following formula.

=IF(AND(ISBLANK([Column B]),NOT(ISBLANK([Column A]))),[Column A][Column C],[Column B][Column C])

Result: