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Tuesday, October 11, 2011

Math 6 Honors ( Periods 1, 2, & 3)

Exponents and Powers of Ten 3-1
When two or more numbers are multiplied together--each of the numbers is called a factor of the product.

A product in which each factor is the SAME is called a power of that factor.

2 X 2 X 2 X 2 = 16. 16 is called the fourth power of 2 and we can write this as
24 = 16

The small numeral (in this case the 4) is called the exponent and represents the number of times 2 is a factor of 16.
The number two, in this case, is called the base.

When you are asked to evaluate... simplify... solve... find the answer
That is,
Evaluate
43 = 4 X 4 X 4 = 16 X 4 = 64

The second and third powers of a numeral have special names.
The second power is called the square of the number and the third power is called the cube.

We read 122 as "twelve squared" and to evaluate it
122 = 12 X 12 = 144

Powers of TEN are important in our number system.
Make sure to check out the blue sheet and glue it into your spiral notebook
First Power: 101 but the exponent is invisible = 10
Second Power: 102 = 10 X 10 = 100
Third Power 103 = 10 X 10 X 10 = 1000
Fourth Power 104 =10 X 10 X 10 X 10 = 10,000
Fifth Power 105 = 10 X 10 X 10 X 10 X 10 = 100,000

Take a look at this list carefully and you will probably see a pattern that we can turn into a general rule:

The exponent in a POWER of TEN is the same as the number of ZEROS when the number is written out.

The number of ZEROS in the product of POWERS OF TEN is the sum of the numbers of ZEROS in the factors.

For example Multiply.
100 X 1000
Since there are 2 Zeros in 100 and 3 zeros in 1000,
the product will have 2 + 3 , or 5 zeroes.
100 X 1000 = 100,000

When you need to multiply other bases:

first multiply each
For example

34 X 2 3 would be
(3 X 3 X 3X 3) X ( 2 X 2 X 2)
= 81 X 8 = 648

What happens when you multiply the same bases?
34 ⋅ 32 = 3⋅3⋅3⋅3⋅3⋅3 or 3 6
We just add the exponents if the bases are the same!!

Well then, what about (34)2 ?
Wait.. look carefully isn't that saying 34 Squared?
That would be (34)(34), right?
.. and looking at the rule above all we have to do here is then add those bases or 4 + 4 = 8 so the answer would be 38.
OR
we could have made each (34) = (3⋅3⋅3⋅3)
so (34)2 would be 3⋅3⋅3⋅3⋅3⋅3⋅3⋅3 or still 38
But wait... isn't that multiplying the two powers? So when raising a power to a power-- you multiply!!
(34)2 = 38

1 to any more is still just 1
15 = 1

0 to any power is still 0!!

Evaluate if a = 3 and b = 5
Just substitute in... but use hugs () we all love our hugs!!
a3 + b2
would be (3)3 + (5) 2
= 27 + 25 = 52




Check out this great Video on the Powers of Ten
POWERS OF TEN

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