How to set digits precision?

I would like to know if it is possible to set digit precision about output ROOT function? For instance, I fill a histogram called “h”. If I take its integral, I do

Result is h->Integral() = 1.6626e+06
If I modify cout precision, I get
h->Integral() = 1662600
My problem is that I would like to know the two last digits which are probably not 0.
How can I set ROOT to get number with a given number of digits?

What precision is your TH1? TH1F, TH1I, … ?

Cheers, Fons.

How can I know that? My histogram is a TH1F but result is the same if I define my histo with TH1D.

If you print more digits you should get a different results, since a TH1F uses single precision and a TH1D uses double precision. However, if the content are all integers (i.e. Counts) the results will be probably the same