I have the starting value of a cell (say A1) as 100 on Jan 1st.

Every month, for a period of 12 months, I need to see the value in A1 increase by 100 i.e. on Feb 1st, March 1st, April 1st...Dec 1st, A1 should read as 200, 300, 400.. with the final value of 1,200 on Dec 1st.

I'd be grateful for any answers, am stumped.