Find a date in a past starting from a future and period of time in years.

Hi guys,

I have been trying to find a start date in the past starting from a future date and a value in years.

The values in year are calculated using the natural logarithm. So the values are not natural numbers.

These are calculations for compound interest. So my goal is find the start date of the investment.

A1 : Period in years
0.999998490334239000000000000000
1.000020042665320000000000000000
1.246123405987020000000000000000
0.170138332745076000000000000000
5.000036554768430000000000000000

B1 : Future Date
17-Jun-2020
2-Jan-2021
31-Mar-2020
23-Apr-2020
6-Aug-2020

C1: The expected Correct date:
17-Jun-2019
2-Jan-2020
2-Jan-2019
21-Feb-2020
6-Aug-2015



***THANK YOU SO MUCH***

How confident are you in those expected correct dates?

If I understand correctly this is what I come up with. They don't all agree.

	A	B	C	D
1	0.99999849	17-Jun-20	17-Jun-19	In C1: =B1-(A1*365.2425)
2	1.000020043	2-Jan-21	2-Jan-20
3	1.246123406	31-Mar-20	31-Dec-18
4	0.170138333	23-Apr-20	20-Feb-20
5	5.000036555	6-Aug-20	6-Aug-15