Originally Posted by

**Soroban** Hello, tom_asian!

Your calculator is correct.

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

This is an Annuity . . .

The formula is: .$\displaystyle A \;=\;D\,\frac{(1+i)^n - 1}{i}$

. . where: .$\displaystyle \begin{Bmatrix}D & = & \text{periodic deposit} \\ i & = & \text{periodic interest rate} \\ n & = & \text{number of periods} \\ A & = & \text{final value}\end{Bmatrix}$

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

. . the periodic deposit is: .$\displaystyle D \:=\:15\% \times \$5,000 \:=\:\$750$

The periodic interest rate is: .$\displaystyle i \:=\:\frac{6\%}{12} \:=\:0.005$

The number of months is: .$\displaystyle n \:=\:3\times12 \:=\:36$

Therefore: .$\displaystyle A \;=\;750\,\frac{1.005^{36} - 1}{0.005} \;=\; 29,502.07872 \;\approx\;\$29,502.08$