Two.
4
It has 3 significant digits.
3 significant digits.
It has two significant digits.
56 in binary is 111000. Unlike the decimal number system where we use the digits.
Five. All nonzero digits are significant and zeros in between significant digits are significant.
The first 3 significant digits of a number are the first 3 digits starting from the left ignoring any leading zeros. So 31456 = 31500 (3 significant digits) The 5 in the "56" rounds the 4 up.
Five. All nonzero digits are significant and zeros in between significant digits are always significant.
Five. All nonzero digits are significant and zeros in between significant digits are always significant.
Five. All nonzero digits are significant and zeros in between significant digits are always significant.
Assuming that the questioner meant 60.9 cubiccentimeters, the answer is 56/60.9 = 0.92 grams per cubic centimeter. Only two significant digits are justified since this is the number of significant digits in 56 g as stated.
Three significant digits.