Few More Math Operators

1. Few More Math Operators Just a couple of more …

2. Practice – the Metro Card • Write a program that asks the value of their current Metro Card • If each ride costs $3.75, compute: • The number of rides they have left • The amount of money they have “left over” after previously stated given rides • The amount of money they need to add to round out an even number of rides

3. Order of Operations • Python follows the order of operations (PEMDAS) • You can use parentheses inside your math expressions to group operations • Example: x = ( (5 + 10 + 20) / 60 ) * 100

4. PEMDAS • Multiplication/Division, Addition/Subtraction must be done in order that it shows up, not interchangeable 3 * 4 / 2 * 5 (3 * 4) / (2 * 5)

5. Converting Math Formulas into Programming Statements • Most math formulas need to be converted into a format that Python can understand • Examples: 10 x y 10 * x * y ( 3 ) ( 12 ) 3 * 12 y = 3 * x / 2

6. Line Continuation • Sometimes expressions can get to be very long • You can use the “ \ ” symbol to indicate to Python that you’d like to continue the expression onto another line ** • Example: x = 5 + 2 / 7 \ + 8 – 12 • This also works for the print ( ) function

7. Mixed Type Expressions • Python allows you to mix integers and floats when performing calculations • The result of a mixed-type expression will evaluate based on the operands used in the expression

8. Exponents • You can raise any number to a power by using the “ ** ” operator • Example: 24 2 ** 4

9. Division Operations • Python contains two different division operators • The “/” operator is used to calculate the floating-point result of a division operation • The “//” operator is used to calculate the integer result of a division operation, it will throw away the remainder. *** This operation will always round DOWN. Examples: print ( 5 // 2 ) # 2 print ( -5 // 2 ) # -3

10. Practice: Time Calculations • Ask the user to input a number of seconds as a whole number. Then express the time value inputted as combination of minutes and seconds >> Enter seconds: 110 That’s 1 minute and 50 seconds!

11. Practice: Time Calculations • There’s actually an operator symbol in Python for what we just did. • Realize, that this will happen a lot. Python has functions and commands that condense the process of a common algorithm. • Let’s take a look …

12. Remainder Operator (modulo) • The modulo operator “ % ” returns the remainder portion of a division operation • This is basically the opposite of the “ // ” operator • Examples: 5 / 2 # 2.5 5 // 2 # 2 5 % 2 # 1 (remainder from divisor of 2)

13. Practice: Time Calculations • Now extend this program to include the number of hours >> Enter seconds: 12074 That’s 3 hours, 21 minutes and 14 seconds!

14. Escape Key “\” • The backslash ( “ \ ” ) is known as an escape key in Python • It tells Python that the character directly following the backslash will not function in it’s regular nature • Example: print(“This class is “Awesome!””) #error! print (“This class is \“Awesome!\””) >> This class is “Awesome!”

15. Examples of the Escape Key • We can use the escape key in various ways: print(“\””) # this will print a quotation mark print(“\n”) # this will print a new line print(“\t”) # this will print an indented tab print(“\\”) # this will print out a back slash

16. Examples of the Escape Key print (“We saw this \n this will print a new line”) >> We saw this this will print a new line

17. Examples of the Escape Key print (“We saw this \t this will print a tab”) >> We saw this this will print a tab

18. Examples of the Escape Key print (“What if we want an actual backslash \\”) >> What if we want an actual back slash \

19. Practice: O Christmas Tree • Using a single print statement, try writing a program that prints out the image of a Christmas Tree • We want this: >> tree /\ / \ / \ I I

20. Examples of the Escape Key print (""" /\\ \n / \\ \n/ \\ \n | | """) >> tree /\ / \ / \ I I

21. format( ) Function • This is a bit premature, but for the sake of your homework, we can use the format( ) function. • This function allows us to format numbers to as many decimal places as we’d like. • It also allows us to insert a comma every three digits, as there are in the real number system (i.e. 12,345,678) • The format function must receive two arguments: • The number it is formatting (for now we’ll always pass floats) • The instructions for formatting

22. format( ) Function Instructions: format ( number , “ , . 2 f ” ) Examples: format ( 100000/7 , “,.2f” ) The result: 14,285.71

23. format( ) Function print ( format ( 100000/7 , “,.2f” ) ) >> 14,285.71 x = format( 100000/7 , “.2f ” ) print( “$” + x ) >> $14,285.71

24. I Woke Up in a New Bugatti

25. Compounded Interest