7.03 Using scientific notation

When writing numbers in scientific notation all of the digits recorded are significant digits
The first value from the previous example (1300 +/- 50) would be written as 1.3 x 103
The second value (2500 +/- 0.5) is written with more digits to show its greater precision as 2.500 x103
(Now the implicit precision (of +/- half a unit of the last significant digit) is clear.)

Using scientific notation also simplifies the task of comparing the precision of two numbers

The rules are :

The number with the most digits is the most precise. e.g. 7.235 x 103 is more precise then 1.25x 10-6

If both numbers have the same number of digits the number with the largest first digit is the more precise e.g 4.25x103 is more precise than 1.75x10-4
(If the first digits have the same value we use the next digit and so on) e.g. 2.763x102 is more precise than 2.748x104