4
Since the first number has 4 sig digs and the second has 7, you have to use the least number of sig digs.
4
It has 3 significant digits.
3 significant digits.
It has two 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.
Three significant digits.
50.4 has 3 significant digits.
There are 3 significant digits in 20.0
It has 6 significant digits.