Ternary form uses only the prefixes above and is the preferred form for this course. Significant figures give the number of digits which establish the accuracy of the measurement. For example, if the average radius of the Earth is given as 6360 km, this implies that the measurement is meaningful only to 10s of km. Calculators give all the digits they can display, so calculator results should have the number of digits reduced to show the accuracy of the result. Symbols and equations in Physics Symbols are used in Physics as a shorthand way of expressing a quantity.
Equations are a shorthand way of expressing a definition or concept.
One of the difficulties in Physics is that different text-books sometimes use different symbols for the same concept and if you do not read the symbol definitions carefully, you may be tricked. When Georg Ohm wrote his famous equation he wrote, . Many a student on seeing that, has confused it with Newton's law of motion, which is written in exactly the same way. Tied in with this is, losing the sense of the symbol. When reading a symbol you should be careful to think or say the concept and not merely the symbol name.