Question

answer each of the following questions in the space provided. 18. explain why the least reliable digit in a measurement is always the final digit. 19. explain the rule for rounding off a calculation to the correct number of significant digits.

Explanation:

1. Measurements are made using instruments with a certain precision. The final digit is an estimate. For example, when using a ruler marked in centimeters, the tenths - place digit is an estimated value based on the observer's judgment, making it the least reliable.
2. If the digit to be removed is less than 5, the preceding digit is left unchanged. If the digit to be removed is 5 or greater, the preceding digit is increased by 1. The result is rounded to the appropriate number of significant digits based on the least - precise measurement in the calculation.

Answer:

1. Measurements involve an estimated final digit due to instrument precision.
2. Remove digits based on value (less than 5: leave preceding digit; 5 or greater: increase preceding digit), round to appropriate significant digits.