why do we use engineering notation instead of scientific notation
Scientific notation Engineering notation (often named "ENG" display mode on scientific calculators) differs from normalized scientific notation in that the exponent n is restricted to multiples of 3. Consequently, the absolute value of m is in the range 1 ≤ |m| < 1000, rather than 1 ≤ |m| < 10. Though similar in concept, engineering notation is rarely called scientific notation. Engineering notation allows the numbers to explicitly match their corresponding SI prefixes, which facilitates reading and oral communication. For example, 6992125000000000000♠12.5×10−9 m can be read as "twelve-point-five nanometers" and written as 6992125000000000000♠12.5 nm, while its scientific notation equivalent 6992125000000000000♠1.25×10−8 m would likely be read out as "one-point-two-five times ten-to-the-negative-eight meters".
Metrication in the United States Although customary units are used more often than metric units in the U.S., the SI system is used extensively in some fields such as science, medicine, the military, automobile production and repair, and international affairs. Post 1994 federal law also mandates most packaged consumer goods be labeled in both customary and metric units.[2] Yet, most Americans are not able to make metric conversions.[3] There exist, however, conversion apps on major smartphone platforms like iOS[4] and Android[5] that can help a person make the necessary conversions.