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Please Note:
The last administration of the old SAT was on 1/22/05. Beginning 3/12/05, only the New SAT will be administered. You should be studying the New SAT book. Go there!
Exponents
Exponents are a shorthand method of describing how many
times a particular number is being multiplied by itself. To write
in
exponent form, we would simply count out how many 3s
were being multiplied together (in this case five),
and then write 35. In written
or verbal form, 35 is stated
as: “three to the fifth power.”There are a number of exponent terms that are important
to know. The SAT will not directly test you on this knowledge, but
you should know these terms if you are going to discuss or learn
about exponents.
When you take the SAT, you should already know the squares
of numbers 1 through about 15. Memorizing this little
chart can save you a lot of time on the test.
You should also know that 2 cubed (23) = 8 and
that 33 = 27,
and—just to be safe—that 43 = 64 and 53 = 125.
Adding and Subtracting Numbers with Exponents
Actually, you can’t add or subtract numbers with exponents.
Instead, you have to work out each exponent to find its value and
then add the two numbers. For example, to add 33 + 42,
you must work out the exponents to get
and
then calculate 27 + 16 = 43.
(You probably don’t need to write out the whole first step when
doing a problem like this one. We included it just to be complete.)
Often, you can work out exponents on your calculator, so figure
out how to use your calculator’s exponent functions before the test.
It can save you time and increase your accuracy.Multiply and Dividing Numbers with Exponents
To multiply two base exponential numbers that have the
same base, all you have to do is add the exponents together:
![]() To divide two same-base exponential numbers, just subtract
the exponents.
![]() If you need to multiply or divide two exponential numbers
that do not have the same base or exponent, you’ll just have to
do your work the old-fashioned way: multiply the exponential numbers
out and multiply or divide them accordingly.
Raising an Exponent to an Exponent
Occasionally you might see an exponent raised to another
exponent, as seen in the following format (32)4.
In such cases, multiply the exponents:
![]() Exponents and Fractions
To raise a fraction to an exponent, raise both the numerator
and denominator to that exponent:
![]() Exponents and Negative Numbers
When you multiply a negative number by a negative
number, you get a positive number, and when you multiply a negative
number by a positive number, you get a negative number. These rules
affect how negative numbers function in reference to exponents.
Square Roots
The square root of a number is the number that, when squared
(multiplied by itself), is equal to the given number. For example,
the square root of 16 is 4, because
A
perfect square is a number whose square root is an integer.The sign denoting a square root is
.
To use the previous example, As with exponents, you
need to know how to multiply and divide square roots.Multiplication and Square Roots
![]() As the example shows, to multiply two square roots, you
should multiply the numbers within each individual square root and
place the product under a single square root.
This rule also works in reverse, so you can take a number
within a
and factor it into perfect squares.![]() Notice in this example that once we separated out 16 from 48,
we could change the
into 4. This
skill is important for the SAT. When dealing with square roots,
you may get an answer that looks quite different from any of the
answer choices. In such situations, you probably have just neglected
to reduce the number within the square-root sign.Division and Square Roots
Just as when you multiply square roots, when you divide
them, you can divide the numbers and place them under a single square
root.
![]() Fractions and Square Roots
To find the square root of a fraction, take the square
root of both the numerator and the denominator. For example,
= sign. For example, = . |
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