There need not be any estimated digit: there could well be exactly 4500.
To round a number, look at the digit to the right of the place you want to round to. If it is 5 or more, change the digit in the place you're rounding to to the next higher digit. If the digit to the right of the place you're rounding to is less than 5, leave the digit in the place you are rounding to as it is. Change all digits to the right of the place you are rounding to to zeros. 198 rounded to the nearest ten is 200.
47184
The answer depends on what the tens digit is greater than, and what the ones digit does then.
6849 and 0213
the estimated digit in 0.0782m is?
There need no be any estimated digit.
The last digit is always the estimated digit in a number
There need not be any estimated digit but, if there must be one, then it is the last digit: 3.
500
There need not be any estimated digit: there could well be exactly 4500.
It is always the last digit.
.0002 is the estimated number
It is the zero at the end.
None of the digits need be estimated.
o
The final 0.