If you need to perform some basic calculations, such as adding, subtracting, multiplying, and dividing, a calculator is probably your best bet. These types of calculations can be done with pen and paper, but a calculator makes it much easier and faster. In a matter of moments you'll have a reliable answer. Besides being accurate and fast, calculators are also very easy to use.
If you want to add several numbers all you have to do is key in the first number then hit the Add (+) key, key in the next number and hit the Add key again. After you enter the final number hit the Add key or the Equals (=) key and you will have your total. Note that you receive a subtotal after every number keyed in when you hit the Add key.
Want to find the average of the numbers you've just added together? After adding the numbers, press the Divide by (/) key and then input the number of numbers you keyed in (i.e., if you added five numbers together, enter "5") and then press the Equals key.
The calculator can subtract numbers just as easily. Key in a number, such as 789, and then hit the Subtract (-) key. Enter another number, such as 456, and then press the Subtract key once again, or the Equals key, and you'll have your answer, in this case 333.
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To multiply numbers together you first enter a number, such as 789, then hit the Multiply (x) key and then enter the second number, such as 456, and then hit the Equals key and your answer, 359,784, will be displayed. If you want to multiply more numbers, simply enter another number and press the multiply key again.
A calculator can also calculate percentages. If you want to know what number is 20 percent of 1,000, enter 1,000, press Multiply, then enter 20 and press the Percent (%) key. This yields the answer, 200. An easy way to remember this is to think of the sequence "1,000 times 20 percent."
Sometimes you make a mistake in entering a number and need to clear it and enter another number instead. If you've entered only the first number, simply hit either the CE or C button ("clear entry" or "clear," respectively). This will give you the opportunity to start over.
If you've already keyed in several operations correctly, then make a mistake, the CE key will let you correct the error without having to go back to the beginning. Pressing the CE key once simply clears the most recent number entry. If you hit the CE key again, or the C key, you'll be returned to zero.
Note that the CE and C keys may be combined on one key marked CE/C, and some calculators have only a C key. If this is the case on your calculator, press the key once to clear the current entry, twice to clear everything you've entered.