Solve for the unknown number of years in each of the following $($Do not round intermediate calculations and round your answers to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$:

$\backslash$table$[[$Present Value,Years,Interest Rate,Future Value$],[$$$,580,10\mathrm{.}73,10,\%,$$$,1,614],[,830,,11,,,2,058],[,18,600,,16,,,259,482],[,21,700,21\mathrm{.}64,13,,,305,503]]$