How many significant digits is found in the number 1.87 x 10^6

While listening to operatic solos, musicians process the lyrics and the tunes in separate brain areas. this most clearly illustrates the functioning of different

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?

In science and physics what is the standard unit of measure for speed?