Tutoring math, you notice the various calculators in use.  The math tutor reveals a couple of important differences among them.

When I was in high school, I used a Texas Instruments scientific calculator.  What model it was I don’t know, but it was virtually the same as today’s TI-30XA.

Back then, the calculators I knew of were all reverse entry:  when you wanted to take the square root of a number, you’d enter the number first, then tap the square root key. You’d take sin, cos, or tan of an angle the same way:  by entering the number first, then the function.  My Texas Instruments TI-30XA and Casio fx-260SOLAR are both reverse-entry.

Among the calculators I see people using nowadays, reverse-entry ones constitute the minority.  More of my students use forward entry calculators:  to get the square root of a number, they tap the square root key, follow by entering the number, then press the “equals” button.  The same goes for sin, cos, and tan:  they enter the function, then the number, and finally “equals”.

Most people know which type of calculator they have and how to use its basic functions. However, some may not realize how their calculator handles brackets.  For example, 4(7+3) means 4x(7+3) to a human.  However, neither my TI-30XA, nor my CASIO fx-260SOLAR recognizes that the brackets mean multiplication.  Each requires you to enter 4x(7+3) in order to recognize you intend to multiply.

On the other hand, my forward-entry SHARP EL-520W does accept 4(7+3) as meaning 4x(7+3); it will give 40 when you enter 4(7+3)=.  However, it will not do so when you enter (7+3)4=.

There are many models of calculator in use today.  A student will do well to experiment with his or hers, to be sure of how it interprets brackets and/or expects functions to be entered.  While many are similar, you can’t always safely assume that your new one works just like your old one.

More differences among various models of calculator will be explored in future posts:)

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.