make up and explain one mnemonic device that is not in math text book.?

Answer 1

Well, naturally I don't know what mnemonic devices are or are not in your text book.

One important mnemonic device for multiplication of two binomials is FOIL, which stands for "first, outer, inner, last," referring to the four pairs of terms that must be multiplied.

Another mnemonic is "Please excuse my dear Aunt Sally," which is abbreviated PEMDAS, the order of operations: parenthesis, exponents, multiplication and division, addition and subtraction.

But I think I just made one up. The lowest common multiple is usually abbreviated LCM. But LCM could also stand for the methodology of finding the LCM itself: list, circle, multiply. In order to find the LCM, you must first list the prime factors of the numbers, then circle the largest grouping of each prime factor, and finally you must multiply together only those groupings. I don't believe I've ever seen this mnemonic device in a text book.