Hello, tom_asian!

Your calculator is correct.

. . You have an extra factor in your formula . . .

The money that you save over the three years will form the deposit on a home.

Assuming that over the three years you salary does not increase,

that you are going to save 15% of your gross monthly income at the start of each month,

and that you earn 6% interest compounded monthly,

determine the total amount you will save in this time.

My solution:

. . . .?

This is an Annuity . . .

The formula is: .

. . where: .

Assuming that the gross monthly salary is $5,000 (you didn't mention it),

. . the periodic deposit is: .

The periodic interest rate is: .

The number of months is: .

Therefore: .