Rates: compare two quantities with different units
Ratios: compare two quantities with the same units
ex. “three out of five dentists recommend toothtaste.”
1/2 exact same meaning 1:2
3/5 -> 3:5
8/10 -> 4:5
200/500 -> 2:5
2/9 -> 2:9
随机应变 ABCD: Always Be Coding and … : хороший
Rates: compare two quantities with different units
Ratios: compare two quantities with the same units
ex. “three out of five dentists recommend toothtaste.”
1/2 exact same meaning 1:2
3/5 -> 3:5
8/10 -> 4:5
200/500 -> 2:5
2/9 -> 2:9
learning the ratio and rates is super important
35 MPH(unit)
-> 35 miles per hour
35 miles / 1 hour
example
$12 / 1hour, 4,000,000babies/1year, 260calories/20 ounces of coke
150 miles / 3 hours = 50 miles / 1 hour -> unit rate
50 miles per hour
A unit rate is any rate where the value of the denominator is 1
pretzelicious: $3.50, 15ounces -> $0.23/ounce
pretztastic: $3.6, 18ounce -> 0.20/ounce
US National Deficit: 17 trillion dollars
$17,000,000,000
1.7 * 10^10
10^4 = 10,000
15,000:standard notation
1.5 * 10^4:scientific notation
negative powers
1.5 * 10^-4 = 0.00015
3.2* 10^-5 = 0.000032
2,700,000,000 -> 2.7 * 10^9
convert to scientific notation
34,000,000 -> 3.4 * 10^7
3/5 = 0.6
1/4 = 0.25
repeating decimal
1/3 = 0.333…
0.3-(bar mean forever)
1/7 = 0.14..
1/4 + 0.32 = 0.57
place values
0.627 -> 6tenth, 2hundredths, 7thousandths
2.18 = 109 / 50
1/4 + 0.32 = 0.57 / 100
what is a fraction?
fraction = part / whole
mixed number has whole number and fractions
1+5/8
common denominators!
8/8 – 3/8 = 5/8 keep denominator same
circumference 88, 28.25
diameter 28, 9
circumference/diameter 3.14, 3.14
π = 3.14
radius * 2 = diameter
c = π*d
d = 3, c = 9.42
Area = πr^2
3^2 = 9, base is three exponent
Exponents are powerful!
first power
3^1 = 3
dividing by the base
3^4
3^3
3^2 = 9
3^1 = 3
3^0 = 1
-1 * 4^2 = -4^2 = -16
(-4)^2 = 16
PEMDAS
parentheses, exponents, multiply, divide, add, subtract
more order of operations
6 / [4- (6-8)]+(-2)^3= -7
area of a square
l*l
l^2
Number Lines
– arrows on each end, zero, marks to indicate scale, positive negative direction
arrow, the lines extend on forever
infinity: goes on forever without limit
+ or –
infinity is the largest on positive
the truth about number line
absolute value: distance from zero, cannot be negative, |number|
sum: the result of adding number together
quatient: the result of division
associative property: +, *
create a project
add views
define layouts
integrate functions
connect ui to code
respond to events
func firstCharacter(of word: String) -> Character {
return word[word.startIndex]
}
firstCharacter(of: "Mom")
import Fundation
func placeFirstLetterLast(myString: String){
}
func placeFirstLetterLast (myString: String) -> String {
var myString = myString
myString.append(firstCharacter(of: myString))
return myString
}
func shortNameFromName(name: String) -> String {
let lowercaseName = name.lowercaseString
let vowelSet = CharacterSet(charactersIn: "aeiou")
}
shortNameFromName(name: "Nate")
//
shortNameFromName(name: "Talia")
//
func lyricsForName(lyricsTemplate: String, fullName: String) -> String {
let shortName = shortNameForName(name: fullName)
let lyrics = lyricsTemplate
.replacingOccurrences(of: "<FULL_NAME>", with: fullName)
.replacingOccurrences(of: "<SHORT_NAME>", with: shortName)
return lyrics
}
The function print, min, max, and abs are a few examples of global functions. Check out a complete list of Swift’s global functions.
print("I'm a global function!")
var initialPrice = 50
var bestOffer = 45
var finalPrice = min(bestOffer, initialPrice)
Anatomy of a function
func functionName (_ parameterName: parameterType) -> returnType {
statements to execute
return object
}
func sumOfStrings(_ aBunchOfStrings: [String]) -> Int {
let array = aBunchOfStrings
var sum = 0
for string in array {
if Int(string) != nil {
let int intToAdd = Int(string)!
sum += intToAdd
}
}
return sum
}
func reverse(_ string: String) -> String {
var reversedString = ""
for character in string.characters {
reversedString = "\(character)" + reversedString
}
return reversedString
}
func warmUp(temperature: Int) -> Int {
return temperature + 10
}
func firstChar(word: String) -> Character {
return word[word.startIndex]
}
func concatenate(firstString: String, secondString secondString){
return firstString + secondString
}
func warmUp(temperature: Int) -> Int {
return temperature + 10
}
func firstCharacter(word: String) -> Character {
return word[word.startIndex]
}
func concatenate(firstString: String, secondString: String)-> String {
return firstString + secondString
}