Rules for deciding the number of significant figures in a measured quantity:

1. All nonzero digits are significant: 1.254 m has 4 significant figures, 1.2 m has 2 significant figures.

2. Zeroes between nonzero digits are significant: 1007 kg has 4 significant figures, 8.07 mL has 3 significant figures.

3. Zeroes to the left of the first nonzero digits are not significant; such zeroes merely indicate the position of the decimal point: 0.001 ft has only 1 significant figure, 0.092 ft has 2 significant figures.

4. Zeroes to the right of a decimal point in a number are significant: 0.083 km has 2 significant figures, 0.2000 mi has 4 significant figures.

5. When a number ends in zeroes that are not to the right of a decimal point, the zeroes are not necessarily significant: 170 miles may be 2 or 3 significant figures, 70,600 L may be 3, 4, or 5 significant figures. For our clas we will consider them as not significant unless there is a decimal point at the end. The potential ambiguity in the last rule can be avoided by the use of scientific notation. For example, depending on whether 3, 4, or 5 significant figures is correct, we could write 50 600 L as: 5.06 × 10^4 L (3 significant figures) 5.060 × 10^4 L (4 significant figures), or
5.0600 × 10^4 L (5 significant figures).

6. $1.569 per gallon has an infinite number of sig. figs. because it is exact. Most conversion factors are exact.

Assignment:

10. Find the result of in two ways: (1.00 + 0.56258)/(1.00 - 0.56258)

a) Work as is and round off the answer to 1 decimal place.

b) round off each number to 1 decimal place first, and then calculate to 1 decimal place.

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