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".
Sentence spacing The desired or correct sentence spacing is often debated but many sources now say additional space is not necessary or desirable.[9] From around 1950, single sentence spacing became standard in books, magazines and newspapers,[10] and the majority of style guides that use a Latin-derived alphabet as a language base now prescribe or recommend the use of a single space after the concluding punctuation of a sentence.[11] However, some sources still state that additional spacing is correct or acceptable. The debate continues.[3] Many people prefer double sentence spacing for informal use because that was how they were taught to type.[12] There is a debate on which convention is more readable; the few recent direct studies conducted since 2002 have produced inconclusive results.[13]