31: Order of Magnitude Literacy

The Oxford English Dictionary states that order of magnitude is “a class in a system of classification determined by size, typically in powers of ten.” One number that differs from a second number by one order of magnitude is ten times bigger than the second number. For example, the mass of the Earth is one order of magnitude greater than that of Mars—in other words it has ten times as much mass. The number 7 is three orders of magnitude less than 7,000 because 7 times 10 to the third power (7 × 10³) is equal to 7,000.

Order of magnitude is an important literacy because it allows us to classify very large magnitudes and very small magnitudes by comparing them to other objects. It is widely understood and used in the scientific community but not widely understood or used by the general public. For example, how would you describe the height of an ant to somebody? Would you say the ant is extremely short? What would that mean? It could mean as short as three feet one inch, or as short as two inches. But if you were literate in order of magnitude, then you would say a human being’s height is roughly three orders of magnitude greater than the height of an ant.