Monthly Calculator

I really need a help as trying to build a calculator from last 5 days unable to do so , i have able to made the calculator for Compound on yearly basis below is the formula and it works great,
fieldname2*POW(1+fieldname3/fieldname6/12,fieldname6/12*fieldname4)

but the problem is i want it tell users if someone has invested X amount on monthly basis for a certain period at particular interest rate what would be the Final amount(compounded)

this is the formula i am trying to make my calculator
FV = P * ( R * ( 1+i )n -1 ) * ( 1 + i )
i
FV = Future Value

P = Monthly amount invested

i = compounded rate of return

As the returns are compounded for every investment instalment, monthly money will be compounded as: i/12.

Similarly, daily daily will be compounded as i/365.

For instance, your monthly investment amount is Rs 10,000 for a tenure of 24 months. You expect 10% annual rate of return. Then the future value would be calculated as below:

Here, P= 10000

i = 10% = (10/100)/12 = 1/120

N= 12 months

FV = 10000 * ( ( 1+1/120)12 -1 )* ( 1 + 1/120 )1/120

Therefore, for the total investment of 1,20,000; amount at the end of the tenure will be Rs 13,20,000

Please if you can help in this, Thanks in advance