You can put this solution on YOUR website! Round 9.64 to the nearest thousandth. You'll notice that there is no thousandth in this number. The number is 9 + 6 tenths + 4 hundredths + 0 thousandths.
You could write it as: 9.6400 and since the digit to the immediate right of the thousandth postion is less than 5 (in this case it is zero), then do not add 1 to the thousandth position. So the number remains as 9.64 and no rounding is required.
(