Abox of nutmeg weighs 99.66 grams. if there are 22 teaspoons of nutmeg in the box, how much does one teaspoon of nutmeg weigh? (round your answer to the nearest thousandth.)

99.66 / 22 = 4.53.  In order to round this answer to the nearest thousandth, we must add one decimal place.  (Tenths, hundredths, thousandths).  We can add as many zeroes AFTER the decimal point as we like without changing the value.

To the nearest thousandth:  4.530 grams.