Calculator Riddles

by David A. Adler, Cynthia Fisher (Illustrator)

Answers to riddles are found by solving related math problems and turning the calculator upside down.

Genres: Mathematics, Nonfiction

32 pages, Paperback

First published September 1, 1995

About the author

David Abraham Adler is an American children's author. He was born in New York City, New York in 1947. He graduated from Queens College in 1968 with a bachelor's degree in economics and education. For the next nine years, he worked as a mathematics teacher for the New York City Board of Education, while taking classes towards a master's degree in marketing, a degree he was awarded by New York University in 1971. In that same year, a question from his then-three-year-old nephew inspired Adler to write his first story, A Little at a Time, subsequently published by Random House in 1976. Adler's next project, a series of math books, drew on his experience as a math teacher. In 1977, he created his most famous character, Cam Jansen, originally featured in Cam Jansen and the Mystery of the Stolen Diamonds, which was published that year.

Adler married psychologist Renee Hamada in 1973, and their first child, Michael, was born in 1977. By that time Adler had taken a break from teaching and, while his wife continued her work, he stayed home, took care of Michael, and began a full-time writing career.

Adler's son, Michael S. Adler, is now the co-author of several books with his father, including A Picture Book of Sam Adams, A Picture Book of John Hancock, and A Picture Book of James and Dolly Madison. Another son, Edward, was the inspiration for Adler's Andy Russell series, with the events described in the series loosely based on adventures the Adler family had with Edward's enthusiasm and his pets.

As of November 2008, Adler has three sons and two grandsons. He lives in Woodmere, New York.

(source: Wikipedia)

Reviews

[Anne Fox · Rating 1 out of 5]

This book has a fatal flaw. For though it encourages young people to do math using a calculator, it ignores a critical math concept that will make this a frustrating book for any young person with a modern calculator. That concept is what's known as "order of operations."

What order of operations dictates is the order in which mathematical operations are performed. The rule is that multiplication and division are performed before addition and subtraction. Multiplication and division are considered equivalent operations as are addition and subtraction. Unless an alternate order is defined using parentheses, this rule is utilized.

So let's take the first equation in the book: 190 X 100 + 19 X 16 = ?

Using order of operations, one would first do the multiplications (190 X 100 and 19 X 16). That reduces the equation to 19,000 + 304, which equals 19,304—not 304,304 as the book proclaims. Given most modern calculators, even simple ones, do order of operations, any youngster trying to get the answer given in the book with their calculator would be frustrated at not getting the "right" answer, which in the book's case is the wrong answer given how the equation is written.

The only way to get the answer the book wants is to do each operation left to right and adding an equal sign between each operation. Thus, the first equation becomes ((190 X 100) + 19) X 16. Doing the order as defined by the parentheses would then go thusly: 190 X 100 = 19,000 + 19 = 19,019 X 16 = 304,304.

The fact that this is a Scholastic publication distributed to schools makes this error even more egregious. Unless the book is revised to reflect proper use of order of operations, I wouldn't use it in a classroom setting.

[Charles · Rating 5 out of 5]

These riddles are based on the appearance of the characters on the readout of a digital calculator. When they are turned upside down, eight of the digits look like letters in the Latin alphabet. A zero is an O, a one is an I, a three becomes an E, a four becomes an h, a five is an S, a seven is an L, an eight is a B and a nine is a G. There are many words that can be made from these eight letters and those words are formed by the execution of a linear sequence of arithmetic operations on the calculator followed by turning it over.
A series of numbers and operations are to be entered on the calculator and they are to be executed in the sequence from left to right, independent of the usual order of operations. The riddle is to determine what the word is before carrying out the calculator operations. They are all simple riddles and the only calculator operations used are addition, subtraction, multiplication and division. Many of the exercises would make fun problems in math tests given to elementary school students. Nothing mathematically complex, just simple fun.