Sharp EL-9900 operation manual Basic Calculations Basic Keyboard, Try it

Chapter 3

Basic Calculations —

Basic Keyboard

In this chapter, we explore more features of this calculator using the Basic Keyboard. Features such as fraction to decimal conversion and the quotient-remainder key, as well as basic arithmetic calculations, will be covered in this chapter.

Note: To try the examples in the chapter, it is required that the Basic Keyboard is already set up by the user. To learn how to set up the Basic Keyboard, read “Changing the Keyboard” in Chapter 1.

1. Try it!

The speed of light is known to be 186,282 miles (approximately 300,000 kilometers) per second. That means light can go around the earth 7 and a half times within a second!

Suppose you are standing at the equator. While the earth rotates over the period of one day, you also rotate around the globe at a certain speed. Knowing the facts above, can you figure out how fast you are traveling, in miles per hour?

Since distance traveled = average speed ⋅ time taken, the following equation can be formed to find out the circumference of the earth (x miles):

x ⋅ 7.5 = 186282

Then,

x = 186282 ÷ 7.5

Since you know the earth turns around once a day (which means, in 24 hours), divide the above “x” with 24 to get a value in miles per hour.

24 ⋅ v = x

x v = 24

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