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 decimal representation of 115 ms is 115 ms, exactly as in the question. If you want it as a decimal fraction of some other quantity then you need to specify that second quantity.
"500 milliseconds", as in the question.
0.005 seconds
It is 50 milliseconds. A decimal representation does not imply a change in the measurement units. If this is required then you need to specify the units into which the quantity is to be converted.
10.0 ms or 0.010 s (1 hundredth of a second)
To write 60 hundredths in decimal form, you would write it as 0.60.
It is already in decimal form>
You would write 11 cents as $0.11 or $.11 in decimal form.
Actually, you already wrote it in decimal form.
To write six and seventeen hundredths in decimal form, you would write it as 6.17.
1.25 is already in decimal form.
139 thousands in decimal form is 139,000139 thousandths in decimal form is 0.139
68 thousands in decimal form is 68,00068 thousandths in decimal form is 0.068