def simple_interest_fv(P, r, t):
    """The future value of a simple interest product consists of the initial deposit, called the
    principal and denoted by P, plus all the interest earned since the money was deposited in the account

    Parameters
    ----------
    P: float
        Principal, initial deposit.
    r: float
        Interest rate
    t: float
        Time, expressed in years.
    """
    return P*(1 + t*r)