No, it is eleven (11) times as much as 0.1!
310 mm = 31 centimeters
320
990 is ten times as much as 99 .1,089 would be ten times bigger.
2900
Six times with a remainder of ten
310
310
310
310
310
3102 rounded to the nearest ten is 3100.
3100
310
310
When rounding 314 to the nearest ten, you look at the digit in the tens place, which is 1. Since 1 is less than 5, you round down to the nearest ten, which is 310.
A decimal number is simply a way of representing a number in such a way that the place value of each digit is ten times that of the digit to its right. A decimal representation does not require a decimal point. So the required decimal representation is 3100, exactly as in the question.