Significant Figures

How many significant figures: 20 pencils.

• 2

• 1

• unlimited

• 3

Answer explanation

A number that is counted has an unlimited number of significant figures.

How many significant figures: 1300 cm.

• 5

• 2

• 4

Answer explanation

Zeros at the rightmost end of a measurement that lie to the left of an understood decimal point are not significant if they serve as placeholders to show the magnitude of the number.

So only 2 here, the non-zero digits are counted.

How many significant figures: 0.0042 grams

• 4

• 5

• 2

Answer explanation

Leftmost zeros appearing in front of nonzero digits are not significant.

How many significant figures: 358.2 ml.

• 4

• 5

• unlimited

Answer explanation

Every nonzero digit is assumed to be significant.

How many significant figures: 2.00 meters.

• 2

• 3

• unlimited

Answer explanation

Zeros at the end of a number and to the right of a decimal point are always significant.

How many significant figures: 145000 cm.

• 2

• 3

• 6

Answer explanation

Zeros at the rightmost end of a measurement that lie to the left of an understood decimal point are not significant if they serve as placeholders to show the magnitude of the number.

How many significant figures: 0.005003 L.

• 2

• 7

• 4

Answer explanation

Two things here:

1) leftmost zeros appearing in front of nonzero digits are not significant.

2) Sandwhiched zeros between nonzero digits are significant.

How many significant figures: 107 voters.

• unlimited

• 3

• 2

Answer explanation

A number that is counted has an unlimited number of significant figures.

How many significant figures: 0.8 meters.

• 2

• 1

• unlimited

Answer explanation

Leftmost zeros appearing in front of nonzero digits are not counted.

• 4

• 5

• 2

Answer explanation

In scientific notation, we don't count the base. We just look at the coefficient and apply the same rules as with numbers written in standard notation.

Here, every nonzero digit is counted as significant so the answer is 2.