Please google for "Rule of 70".

Eric wrote:

I can't make sense of what you wrote.
Also, I need to make sure that the calculated value is the sum of each year
including interest. This should be calculated by adding year1 + year2 + year3
etc
year2 and up should be calculated by =Year1^(1.04*n) where n = the year#

"Barb Reinhardt" wrote:


It should make no difference what the initial year is (I think)

THis is your equation

Initial Value * 1.04^n = 2* Initial Year

Solve for n (which is the # of hears

1.04^N = 2
n log 1.04 = log 2
n = log 2/log 1.04
N = 17.67 years.

If the interest rate changes, your result will change.

HTH,
Barb Reinhardt

"Eric" wrote:


Hello everyone,

I am trying to create a forumla to show pay back time.

If there is a 4% increase each year over the previous year, how many years
it will take until the accrued years will equal A1

The values I will input are "initial year" and A1