Restart running total after X number of rows

[nielf]

I'm trying to come up with a formula that can 'restart' a running total after 12 rows.

Currently my data looks like this where the running total is calculated using the formula in C2 is

=SUM($B$2:B2)

This works fine until I reach row 14. Here I would like the formula to 'restart' so it would be

=SUM($B$14:B14)

.

Is there anyway I can achive this 'restart' by counting the number of rows so I don't have to manually update the formula as I go?

I know it is possible to use the function in a PivotTable but that's not the solution I'm looking for.

 

[gallen]

This line is pointless and will basically copy what is in cell B2.

=SUM($B$2:B2)

you could just as easily have

=B2

I think it must be a typo?

 

[footoo]

=if(mod(row(),12)-2=0,b2,b2+c1)

 

[nielf]

@gallen,

Yes, that is the case for the first row. However, I'm looking for the running total so I need that formula for all other rows. E.g. C3 would be

=SUM($B$2:B3)

and not just

=B3

.

 

[nielf]

=if(mod(row(),12)-2=0,b2,b2+c1)

Thank you. That was exactly was I was looking for.

If you have time - could you perhaps explain how the formula works?

 

[footoo]

Thank you. That was exactly was I was looking for.

If you have time - could you perhaps explain how the formula works?

ROW function :
https://support.office.com/en-us/ar...pId=xlmain11.chm60056&ui=en-US&rs=en-US&ad=US

MOD function :
https://support.office.com/en-us/ar...pId=xlmain11.chm60087&ui=en-US&rs=en-US&ad=US

Can revise the formula to :
=if(mod(row(),12)=2,b2,b2+c1)