There's one, because after the decimal point the first non zero number is 6.
No, one of them.
One.
6 significant figures.
There are 6 significant figures in this number.
If you mean "How many significant figures are there in 314.721 meters then the answer is 6.
6
6
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.
6 significant figures.