President
Erthry is not a prefix. The only prefixes that begin with E are the prefixes en-, ex-, and extra-. Erthry is not a suffix either.
Area code 415 serves San Francisco and Marin County, California, but there is no 138 prefix. Telephone prefixes in North America (USA, Canada, etc.) cannot begin with 1.
Words that begin with the prefix "ie" include "ielectric," "iefficient," and "iempower."
HexagonHexadHexagramHexadicHexagonalAll of the above mean "six of something"HexahedronHexahedraAll of the above mean a "six sided shape"
My names of chemical compounds begin with the prefix tetra, such as Carbon tetrachloride and Tetrahydrocanabinol.
Part of learning prefixes and suffixes relies on memorization, knowing what is and isn't a word. Second, you begin to notice patterns between groups of prefix words, such as the 'dis-' prefix. Third, if you play and practice speaking various words you can often tell when a prefix is correct, like uncomfortable is correct, but unpresent is incorrect.
Some words that begin with the prefix "ambu" include ambulance, ambulatory, and ambulate.
incredible
insert
outside
Some words that begin with the prefix "aug" include: augment, august, augur, and augury.
Words that begin with the prefix "ir" and mean "not" include irregular, irresponsible, irrelevant, and irrational.