MathChat

Welcome to the second in my series of posts about the “secrets of the calculator.” In my first post on this topic I explained how the 1/x key can make it easier to input certain expressions. If you missed that one, just click here.

Today I’d like to talk about another key that is quite useful, the “EE” key.

What in the world is the EE key, and what does it do?

At first hearing, EE sounds a bit like the call of a monkey.

But actually, the EE key is what you use to represent the value of really LARGE or really SMALL numbers. That is because the EE key allows you to represent the value of numbers with scientific notation. When you press the EE key (on some calculators you first press the 2nd key, then the EE key), you get the power to which the number 10 is raised in scientific notation.

Example 1:  Suppose you want to represent 10^4

Just use these keystrokes (→ means “next keystroke”):  EE → 4 → =/Enter

The display should read:  10,000. Why? Because the keystrokes you entered are equivalent to 10^4.

Note that the calculator assumes a base of 10 whenever you press the EE key. That saves time.

Example 2:  Suppose you want to represent 10^–4

Use these keystrokes:  EE → –4 → =/Enter

The display should read:  0.0001. That is because the keystrokes you entered are equivalent to 10^-4.

Example 3:  Suppose you want to represent 10^0

Use these keystrokes:  EE → 0 → =/Enter

The display should read:  1, since 10^0 = 1

Now if you want to input expressions that involve scientific notation but with other numbers involved, you still use the EE key, and it makes the process quite easy.

Example 4:  Suppose you want to represent 7.2 x 10^4

Just use these keystrokes:  7.2 → EE → 4 → =/Enter

The display should read:  72,000, since 7.2 x 10^4 = 72,000

Example 5:  Suppose you want to represent 7.2 x 10^– 4

Just use these keystrokes:  7.2 → EE → –4 → =/Enter

The display should read:  0.00072 , since 7.2 x 10^– 4  =  0.00072

Example 6:  Suppose you want to input and find the value of the following fractional expression:

(2.6 x 10^3)(.53 x 10^2)
(.024 x 10^5)(9.7 x 10^6)

All you’d have to enter is this:

First, the denominator:

.024 → EE → 5 → x → 9.7 → EE → 6 → =/Enter

Then hit the 1/x key to push this number into the denominator, as I explained in this post.

Then continue by multiplying by the numerator’s value:

x → 2.6 → EE → 3 → x →  .53 → EE → 2 →  =/Enter

After pressing the last “=/Enter” you will get the answer.

Do you see how nice and streamlined this in comparison to entering this expressions with 10’s and exponent keys? Calculator programmers developed this key to make the process fast and easy.

Finally, in case you’re wondering why the key has the label EE, I’ve read two explanations:  1) EE stands for Engineering Exponent, 2)  the letters stand for Enter Exponent. No one seems quite sure which interpretation is correct, so feel free to take your pick.