Besides the number buttons and those for the basic arithmetic operations of addition, subtraction, multiplication and division, a scientific calculator has an array of function buttons. Some of these calculate exponents, square roots and trigonometric functions. Among the function buttons, you'll find one with a minus sign (-) or a plus/minus sign (+/-) that changes the sign of the displayed number. That's the one you should use to display a negative number. It's more reliable than the subtraction operator button, which doesn't always work the way you expect.
Inputting a Negative Number
If you want to input a negative number, press the sign change button before you enter the number. If you forget to do this, and you enter the number first, it's no problem. The sign of the number will change when you press the sign change key, even if you've already entered the number.
Note: On some calculators, you have to enclose the negative number in brackets for the calculator to handle it properly. This isn't true for all calculators. For example, it isn't necessary on the scientific calculator that comes on iPhones.
Working With Negative Numbers
The benefit of a sign change key becomes obvious when you have to do arithmetic operations – particularly subtraction – that involve negative numbers. On a regular calculator, the subtraction key won't change the sign of the displayed number unless you first enter 0. This makes things confusing when you have to also perform operations with more than one negative number.
If you have a scientific calculator, you can avoid this confusion. Here's how to subtract -2 from -5 on a scientific calculator. The brackets are necessary only on some calculators:
- Press the open bracket key "(" (optional).
- Press the sign change key.
- Enter the number from which the other number will be subtracted, which in this case is 5.
- Press the close bracket key ")" (optional).
- Press the subtraction operation key.
- Press the sign change key.
- Press the open bracket key if needed (your calculator might automatically add one when you hit the sign change key).
- Enter the other number, which in this case is 2.
- Press the close bracket key, if needed.
- Press the equal sign key.
The answer (-3) will appear on the display.
The procedure is just as easy for the three other operations. Simply press the button for the desired operation instead of the subtraction button in Step 3.
You'll get an error message if you enter a negative number and then press the square root function button. That's because the square root of a negative number doesn't exist. You can however, find the cube root and other odd-numbered roots by using the y root x button.
About the Author
Chris Deziel holds a Bachelor's degree in physics and a Master's degree in Humanities, He has taught science, math and English at the university level, both in his native Canada and in Japan. He began writing online in 2010, offering information in scientific, cultural and practical topics. His writing covers science, math and home improvement and design, as well as religion and the oriental healing arts.