### Upload assignment 3

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 %% Cell type:markdown id: tags: # Alternating sum **Learning goals:** * Loops **Starting Out with Python:** * Chapt. 4.2-4.3 In this assignment you are going evaluate the sum of numbers, based on user input. %% Cell type:markdown id: tags: ## a) Write a program that reads in an integer $n$ from the user and evaluates the series below. **$1^{2}-2^{2}+3^{2}-4^{2}+5^{2}-\cdot \cdot \cdot \pm n^{2}$** Notice that all the even numbers have a negative sign and all the odd numbers have a positive sign. Also recall that the name of your variable ***cannot*** be **sum**, as this is the name of a function in python. Also remember that range() is inclusive for the starting number but exclusive for the end number. Example run: python n = 7 The sum of the series is 28  ***Write your code here*** %% Cell type:code id: tags:  python  %% Cell type:markdown id: tags: ## b) Write a new program such that it ends the iteration **before** the sum of the numbers is greater than the nonnegative integer $k$. That is the sum at the last term should be printed before it surpasses the number $k$. Keep track of how many terms from the series which have been included in the sum and print this out with the result. Example run: python k = 6 The sum of the numbers before the sum surpassed k is -10. Number of iterations: 4  python k = 12 The sum of the numbers before the sum surpassed k is -10. Number of iterations: 4  python k = 15 The sum of the numbers before the sum surpassed k is -21. Number of iterations: 6  ***Write your code here:*** %% Cell type:code id: tags:  python 
 %% Cell type:markdown id: tags: [Back to Assignment 3](_Oving3.ipynb) # Code Comrehension **Learning Goals:** * Understanding code The code below cannot be run, here you have to think about the answers! About. 20% of the exam is about understanding code so look at this as valuable training! %% Cell type:markdown id: tags: ### task a) %% Cell type:markdown id: tags: **a)** What is printed in the code below? %% Cell type:markdown id: tags: python a=345 b='' while a or b=='': b=str(a%2)+b a=a//2 print(b)  %% Cell type:markdown id: tags: **Answer:** < Doubleclick here to write your answer > %% Cell type:markdown id: tags: ### task b) %% Cell type:markdown id: tags: **b)** What is printed in the code below? %% Cell type:markdown id: tags: python for x in range(0, 10, 2): print(x, end='') if x%4==0: print( ": This number is dividable by 4") else: print()  end="" makes the next print() at the same line as the previus print(). Normally it would print at the next line. %% Cell type:markdown id: tags: **Answer:** < Doubleclick here to write your answer > %% Cell type:markdown id: tags: ### task c) %% Cell type:markdown id: tags: **c)** What is printed in the code below? %% Cell type:markdown id: tags: python i = 1 while i<10: i = i*2 print(i)  %% Cell type:markdown id: tags: **Answer:** < Doubleclick here to write your answer > %% Cell type:markdown id: tags: ### task d) %% Cell type:markdown id: tags: **d)** What is printed in the code below? %% Cell type:markdown id: tags: python i = 1 j = 3 while j>0: i = i*2 j = j - 1 print(i) %% Cell type:markdown id: tags: **Answer:** < Doubleclick here to write your answer > %% Cell type:markdown id: tags: ### task e) %% Cell type:markdown id: tags: **e)** What is printed in the code below? python i = 5 for x in range(i): for y in range(x+1): print("*", end="") print() This is a double loop, which might be unknown for many. Try it anyways! How does a loop within a loop actually work? see page 176 in Starting out with Python. %% Cell type:markdown id: tags: **Answer:** < Doubleclick here to write your answer >