Since they both have the same whole number of 9, we can't look at that.
What you do is first look at the tenths place: \(\displaystyle \L \;9.\underbrace 9_{}\,,\,9.\underbrace 0_{}9\,,\,9.\underbrace 9_{}90\)
Since
9.9 and
9.990 both have a tenths digit greater than
9.09 and their tenth digit is the same, we will now compare the hundreths place of these two numbers to see the greater.
So the smallest is: \(\displaystyle \L \;9.09\,\) since it has the smallest tenth digit.
Now we compare the hundreths place:\(\displaystyle \L \;9.9\underbrace 0_{}\,,\,9.9\underbrace 9_{}\)
Since the
9.9 has an understood zero after it, you know that is less than nine.
So your biggest number is:\(\displaystyle \L \;9.99\)
