"zalle78" wrote:
I but a machine for $1.000. It's depreciated with 10%
of it's balance annually. The end value is $1500. How
many years will it take before it reaches this level?

I assume you meant the purchase price to be $10,000 or something else much
greater than 1500.

Put the following into C1, for example:

=NPER(-10%,0,-10000,1500)

Note the opposite signs used for PV (-10000) and FV (1500). Note that the
annual rate is negative (-10%).

As a check, put 10000 into B1, put =A1+1 into A2, and put =B1*(1-10%) into
B2. Copy A2:B2 down through A18:B18 or until you see close to 1500, but
slightly more (probably).

In fact, you will get "exactly" 1500 (with some infinitesimal rounding
error) if you put the following formula into B19: =B18*(1-10%)^(C1-A18).