There are three.
There are three of them there.
0.00860 has three significant figures.
635 is already a three significant figure number.
9010
Three.
Three
Three.
Three.
That depends on whether the dot before the question mark is a period or a decimal point. 100 has one significant figure. 100. has three significant figures.
It is 25.7 when rounded to 3 significant figures
their are 2 significant figueres in 1.0