Question

What is the significant digit of 2.021?
CLASS 11-PHYSICS-UNITS AND MEASUREMENTS

Answer 1

Answer: in multiplication or division, the computed result should not contain greater number of significant digits than in the observation which has the fewest significant digits. Examples: (i) 53 × 2.021 =107.113

Explanation:

Answer 2

Answer:

2.021

Sig Figs

4

2.021

Decimals

3

2.021

Scientific Notation

2.021 × 100

E-Notation

2.021e+0

Words

two point zero two one

Rounded to Fewer Sig Figs

3     2.02            2.02 × 100

2       2.0                 2.0 × 100

1        2                  2 × 100

Significant Figures

Every measurement results in a number that includes reliable digits and uncertain digits. Reliable digits plus the first uncertain digit are called significant digits or significant figures.These indicate the precision of measurement which depends on least count of measuring instrument.

Example, period of oscillation of a pendulum is 1.62 s. Here 1 and 6 are reliable and 2 is uncertain. Thus, the measured value has three significant figures.

Rules for determining number of significant figures

All non-zero digits are significant.

All zeros between two non-zero digits are significant irrespective of decimal place.

For a value less than 1, zeroes after decimal and before non-zero digits are not significant. Zero before decimal place in such a number is always insignificant.

Trailing zeroes in a number without decimal place are insignificant.

Trailing zeroes in a number with decimal place are significant.

Cautions to remove ambiguities in determining number of significant figures

Change of units should not change number of significant digits. Example, 4.700m = 470.0 cm = 4700 mm. In this, first two quantities have 4 but third quantity has 2 significant figures.

Use scientific notation to report measurements. Numbers should be expressed in powers of 10 like a x 10b where b is called order of magnitude. Example, 4.700 m = 4.700 x 102 cm = 4.700 x 103 mm = 4.700 x 10-3 In all the above, since power of 10 are irrelevant, number of significant figures are 4.

Multiplying or dividing exact numbers can have infinite number of significant digits. Example, radius = diameter / 2. Here 2 can be written as 2, 2.0, 2.00, 2.000 and so on.

Explanation:

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