3 significant figures.
There are 1000 metres in one kilometre. Therefore, 21500 metres is equal to 21500/1000 = 21.5 kilometres.
4
It has two significant digits.
It has 3 significant digits.
3 significant digits.
Five. All nonzero digits are significant and zeros in between significant digits are 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.
Five. All nonzero digits are significant and zeros in between significant digits are always significant.
50.4 has 3 significant digits.
There are 4 significant digits in 5600.
This number has seven significant digits.