Use a Calculator

People use calculators to solve complex calculations, when mental calculation would be difficult, and when paper and pencil solutions would be inefficient or too slow. People also use calculators to determine if the results of computation, done other ways, are reasonable. As learners learn how to use a calculator, they should also learn when the use of a calculator is necessary and appropriate. By learning the arithmetic skills in Math Skill Builders, learners will not have to rely on calculators for computation.

Before students can successfully use a calculator to perform calculations and solve problems, they should become familiar with the keys on the calculator and how to enter problems. Calculators have these kinds of keys:

Number entry keys: 0-9
Function keys:

+ (addition)
- (subtraction)
* (multiplication)
/ (division)

Control keys :

= (equals, to solve the problem entered)
Control keys include keys to:
remove the last number
clear the whole problem
put numbers in memory
retrieve numbers from memory
(sometimes C; CE; CM; M+; RM)

Learners need to practice using a calculator. First they should practice putting in single digit numbers and numbers with many digits, using the number keys. Then they should practice using the number keys and the function keys to put in problems. Learners should also practice using the control keys, and be able to remove the last number, or to clear the whole problem and start a new problem.

Usually, you press the numbers on the calculator in the order they appear in the problem. (On some calculators you may need to enter the numbers first, and then the function key.) For example if the problem is:

187 + 42

Enter the numbers 1,8,7
Then press + to add
Then enter the numbers 4, 2
Then press = to get an answer.

Finding the answer to a division problem with a remainder takes a few extra steps on the calculator. For example, follow these steps to solve this problem:

1754 / 23

1. In this problem the divisor is 23, and the dividend is 1754. Enter
   
   1754 / 23 =
   in the calculator to divide the numbers in the problem.
   The answer you get is 76.26086.
   The whole number part of the answer (76) is the quotient.
2. Multiply the quotient (76) by the divisor (23).
   
   76 X 23 = (The answer is 1748)
3. Subtract the product (1748) from the dividend (1754) to find the remainder:
   
4. The answer is 76 remainder 6.