# Annuity with deposits solved for number of periods given total value

Hi can someone help me solve for t in the equation below? total = p (i +1) + d * (1+i)t-1 / i * (1 + i)

Trying to figure out the formula for "how long will it take me to save X if I have Y to start and deposit d dollars every period. Very familiar with TMV, but solving this equation for t is a bit above my level. I know periods and interest rates have to be in the same terms and such, just trying to solve for t or number of periods in this case.

• Personal finance SE probably isn’t the place to solve an equation. I did it by straightforward algebra to isolate a (1+i)^t term then taking the logarithm of both sides to get an expression for t. It isn’t terribly useful though since one would typically solve it with a financial calculator or an online calculator or app. Also there’s no math plugins here as you noticed so formatting the equation is not supported. If for some reason you really want the equation I can check my work and create an image or something. – T. M. May 17 '19 at 19:47