# Numbers and Operations

## Presentation on theme: "Numbers and Operations"— Presentation transcript:

Numbers and Operations

Families of numbers

The Numbrella Complex numbers Real Numbers Imaginary Numbers |
Rational Numbers Irrational Numbers Integers Whole Numbers Natural Numbers a+bi Has a real and an imaginary component i—or bi Can be expressed as a fraction Can’t be expressed as a fraction All “non-decimal” values All positive integers and zero All positive integers

Natural Numbers Counting Numbers 1, 2, 3, 4, 5, …

Counting Numbers & Zero
Whole Numbers Counting Numbers & Zero 0, 1, 2, 3, 4, 5, …

Positive and Negative Numbers and Zero
Integers Positive and Negative Numbers and Zero …, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, …

Can be expressed as the ratio of 2 integers
Rational Numbers Can be expressed as the ratio of 2 integers

Cannot be expressed as the ratio of 2 integers
Irrational Numbers Cannot be expressed as the ratio of 2 integers Non-terminating, non-repeating integers Π

Examples: The approximate value of √7: √4 = 2 √9 = 3 so √7 is approx. 2.6 Determine the approximate value of the point: The point is about 3.4

Scientific Notation

Significant Digits Rules
1-9 are significant 0’s between digits are significant 0’s at the end suggest rounding and are not significant Leading 0’s are not significant 0’s at the end of a decimal indicate the level of precision Every digit in scientific notation is significant

Examples 1024 4 Significant Digits 1000 1 Significant Digit
ALWAYS HAVE ONE SIGNIFICANT DIGIT IN FRONT OF THE DECIMAL FOR SCIENTIFIC NOTATION

Examples Expand: 2.15 x x 103 a negative exponent tells you to move the decimal to the left Write in scientific notation: 3,145,062 2,230, move the decimal so that there is only one digit in front and count the number of spaces you have moved—moving left is positive here and right is negative x x x 10-4

Examples Simplify: do the math on the numeric portion as you normally would, use the rules of exponents on the powers of ten, place in standard scientific notation to finish (one digit before the decimal) (2.75 x 102)(4 x 103) 11 x x 106 5 x 10 x 108 .5 x 10-2 5 x 10-1

Percent

Percentages Convert 20% to a decimal Convert .45 to a percentage
20/100= .2 Convert .45 to a percentage .45 * 100= 45% Convert ¾ to a percentage ¾= * 100=75%

Examples: What is 7 percent of 50?
.07 * 50 = 3.5 A CD that normally costs \$15 is on sale for 20% off. What will you pay Option 1 .2 * 15 = = 12 Option 2 If it is 20% off you will pay 80% .8 * 15 = 12

Order of Operations

PEMDAS A R N T H E S I X P O N E T S M UL T & D I V A D & S U B
From left to right

Examples: 30 ÷ 10 • (20 – 15)2 30 ÷ 10 • ÷ 10 • 25 75 Parenthesis Exponents then mult and div From left to right

Absolute Value

Formal definition Absolute value is the distance from the origin and distance is always positive.

Examples |6| |-7| |-9-3| |-12| 12

GCF and LCM

Examples GCF—greatest common factor 20 35 60 24 5 4 5 7 6 10 3 8
What is the largest number that divides all the given numbers evenly 22* * *3* *3 WHAT DO THEY SHARE? * 3=12

Examples LCM—least common multiple 20 35 60 24 5 4 5 7 6 10 3 8
What is the smallest number that the given number go into evenly 22* * *3* *3 WHAT IS THE LAGEST VALUE SHOWN IN EACH? 22*5*7= *3*5=120

Using Proportions

What is a proportion and how can you solve a problem with it?
If Sue charges a flat rate each hour to babysit. If she ears \$44 for 8 hours. What will she earn for 5 hours? PRIMARY RULE: If you put the \$ amount in the numerator on one side put the same value in the numerator on the other side. Etc. cross mult = 8x 27.5= x Sue will earn \$27.50 for 5 hours.

Distance and Work Problems

Distance problems

Example It took the Smith’s 5 hours to go 275 miles. What was their average rate of speed? D=rt 275 = r(5) 55 = r They went about 55 mph

Work problems Use the reciprocal of the time for the rate of work
W for 1st person =hours worked * rate of work W for 2nd person =hours worked * rate of work Total job always =1 1 = W for 1st person + W for 2nd person

Example: John and Sam decide to build a bird house. John and build the bird house in 5 hours working alone. Sam can do it in 8 hours alone. How long will it take if they work together? It will take them 3.08 hours to make the bird house.

Estimation What are the critical terms for estimation?

The “detail” associated with a measurement
Precision The “detail” associated with a measurement

Calculations with two different levels of precision can only be accurate to the least precise measure. Add a slide with two examples

How correct a measurement is
Accuracy How correct a measurement is The smaller the unit of measure the more accurate your measurement

The amount of difference between your measurement and the true value
Error The amount of difference between your measurement and the true value

Examples: Jim bought 3 pounds of nails for \$ Which amount is closest to the price per pound? Round off and check above and below 15/3 = 5 and 18/3 = 6 A reasonable values would be between \$5 and \$6 but closer to \$5

Conversions

Length Conversions 1 inch = 2.54 cm 12 inches = 1 foot 3 feet = 1 yard
5280 feet = 1 mile How many inches are in 1 yard? 1 yard = 3 feet 1 foot = 12 inches 3x12 =36 inches

Fluid Conversions 3 Teaspoons = 1 Tablespoon 2 Tablespoons = 1 ounce
8 ounces = 1 cup 2 cups = 1 pint 2 pints = 1 quart 4 quarts = 1 gallon

Weight Conversions 16 ounces = 1 pound 2.2 pounds = 1 kilogram
2000 pounds = 1 ton

milli- centi- -meter = distance -gram = weight -liter = fluid kilo-