121004.5CROSS MULTIPLY.100X1058.04100X100 1058.04100X10.5804 $10.5...

235.12

100

^4.5

Cross multiply.100x1058.04

100x

100

^1058.04

100

x10.5804 $10.58

R

^{ATE OF}

C

^HANGE

If a pair of shoes is marked down from $24 to $18, what is the percent of decrease?To solve the percent, set up the following proportion:partwhole changeoriginal cost %100

24

18

24

100

^x

6

24x600

24x

24

⁶⁰⁰

24

x25% decrease in priceNote that the number 6 in the proportion setup represents the discount, not the sale price.

S

^IMPLE

I

^NTEREST

Pat deposited $650 into her bank account. If the interest rate is 3% annually, how much money will she havein the bank after 10 years?

–

A R I T H M E T I C

–

Interest = Principal (amount invested) ×Interest rate (as a decimal) ×Time (years) or I= PRT.Substitute the values from the problem into the formula I= (650)(.03)(10).Multiply I= 195Since she will make $195 in interest over 10 years, she will have a total of $195 + $650 = $845 in heraccount.ExponentsThe exponent of a number tells how many times to use that number as a factor. For example, in the expres-sion 4

³

, 4 is the base numberand 3 is the exponent, or power. Four should be used as a factor three times: 4

³

= 4×4×4 = 64.Any number raised to a negative exponent is the reciprocal of that number raised to the positive expo-3

²

1

¹

₃

2

²

¹

9

nent:

1

2

2 255Any number to a fractional exponent is the root of the number:2527

¹

³

2

³

273256

¹

⁴

2

⁴

2564Any nonzero number with zero as the exponent is equal to one: 140° = 1.Square Roots and Perfect SquaresAny number that is the product of two of the same factors is a perfect square.1 ×1 = 1, 2 ×2 = 4, 3 ×3 = 9, 4 ×4 = 16, 5 ×5 = 25, . . .Knowing the first 20 perfect squares by heart may be helpful. You probably already know at least thefirst ten.