Significant DigitsUnit 1 – pp 56 – 59 of your book

Mrs. Callender

Significant Digit Rules

1. All nonzero numbers are significant.

1.345 g has 4 significant digits.

2. Zeros between nonzero numbers are significant.

1.05 g has 3 significant digits.

Significant Digit Rules

3. Zeros before nonzero numbers but after the decimal place are NOT significant.

0.0033 g has 2 significant digits.0.0033 g the zeros are PLACEHOLDERS

4. Zeros after the decimal AND after nonzero numbers are significant.

1.500 g has 4 significant digits.1.500 g the zeros are significant.

Significant Digit Rules

5. Zeros both at the end of a number but to the

left of a decimal points is NOT significant. 1,000 L has 1 significant digit1,000 L the zeros are PLACEHOLDERS

What about 200 red cars?

Is there a measuring device for cars?

Counting numbers have an infinite number (∞) of significant digits.

Conversion factors are exact: 1 inch = 2.54 cm

This has ∞ number of significant digits

Rounding rules for number 5.

Math: when rounding with a 5 the number would get “rounded up”.

4.5 rounds to 5

In Science……Odd numbers: 1,3,5,7,9 Round up with 5

Even numbers: 0,2,4,6,8 No rounding with 5

Round 1.35 cm to 2 significant digits.

Round 1.45 cm to 2 significant digits.

1.4 cm

1.4 cm

Ad

ditio

n a

nd

S

ub

tractio

nAdd/Subtract then round to the data

with the fewest number of DECIMAL places.

24.5001 cm

123.45 cm

+ 0.378 cm

148.3281 cm

3 decimal places

2 decimal places

4 decimal places

Answer can only have 2 decimal places.

Round 148.3281cm to 148.33 cm

**

Mu

ltiplic

atio

n a

nd

D

ivis

ion

Multiply/Divide then round to the data with the fewest number of Significant Digits.

24.5001 cm

X 0.378 cm

9.2610378 cm2

3 sig. digs

6 sig. digs.

Answer can only have 3 significant digits.

Round 9.2610378 cm2 to 9.26 cm2

**