Assume you have real dates in A1 to K1 (Jan to Dec)
In A2, enter 100
In B2, enter =if(mod(month(b1)-1,3)<0,a2,a2+100)
Copy across to K2

If you don't have real dates as headers, but simply Text (Jan to Dec), you
can change "month(b1)" to "column(b1)"

Regards,
Fred.

"chandra1961" wrote in message
...
i have 12 months from january to december , each month say Rs 100 as
input
whenever january or april or july or october months ie every quarter i
have
to increment rs 100,
for example when jan comes increment rs 100 to the cell other months no
icrement
for april comes only april incremented likewise every quarter

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