Franklin wishes to have $10 million in his retirement savings plan in 25 years. His bank is offering him an investment that promises a return of 8% compounded monthly. Franklin wishes to deposit money every six months. Franklin's semi-annual deposit is closest to:

Franklin wishes to have $10 million in his retirement savings plan in 25 years. His bank is offering him an investment that promises a return of 8% compounded monthly. Franklin wishes to deposit money every six months and plans to make his first deposit immediately. Franklins semi-annual deposit is closest to:

The questions are similar only one says deposit immediately the other does not so they have different answers.

If possible can someone solve these but with the formulas and not on excel (nor a financial calculator) so I understand all the steps.

Thank you!