Try the following,
N[NestList[Cos, 15/10, 10], 10]
{*
{1.500000000,0.07073720167,0.9974991672,0.5424049923,0.8564697089,0.6551088018,
0.7929816458,0.7017241683,0.7637303113,0.7222610821,0.7503128857}
*}
SetAccuracy[NestList[Cos, 1.5, 10], 10];
SetPrecision[NestList[Cos, 1.5, 10], 10];
NumberForm[NestList[Cos, 1.5, 10], {10, 10}]
{*
{1.5000000000,0.0707372017,0.9974991672,0.5424049923,0.8564697089,
0.6551088018,0.7929816458,0.7017241683,0.7637303113,0.7222610821,0.7503128857}
*}
Edit
With F1 or ?? you can find more information:
?? SetAccuracy
?? Accuracy
?? SetPrecision
?? Precision
?? NumberForm
InputForm
, or otherwise change the print precision in Preferences. I wouldn't recommend jumping to arbitrary precision numbers without a good reason, nor reassigning precision usingSetPrecision
without a very good understanding of what it does. $\endgroup$