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Grade 12 Challenge: Algorithms & Real Computing Worksheet with Answers

Grade 12 (US) · Year 13 (UK) · Class 12 (India) · Computer Science

Unit 5: Going FurtherReal-World ChallengeChallenge

Computing as engineers meet it: password-cracking time, binary search on billions, subnets, two's complement and Python surprises. This free high school worksheet has 12 questions and a full answer key. Print it or save it as a PDF — every answer is checked by code, not guessed.

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Challenge: Algorithms & Real Computing

Grade 12 · Computer Science

Score___ / 12

Name

Class

Date

Learning goal: Real-World Challenge

Directions: Read each question carefully and write your answer on the line.

Example

A network is given the IPv4 block /25. How many usable host addresses does it have? (Two addresses are reserved.)

Answer: 126

  1. 1

    An attacker can try 1 million passwords per second. A password is 8 lowercase letters (26 options each). How many hours to try every possibility? Give 1 decimal place.

  2. 2

    A network is given the IPv4 block /28. How many usable host addresses does it have? (Two addresses are reserved.)

  3. 3

    Binary search is used on a sorted list of all 8.1 billion people on Earth. In the worst case, how many items must it check?

  4. 4

    An attacker can try 1 million passwords per second. A password is 7 lowercase letters (26 options each). How many hours to try every possibility? Give 1 decimal place.

  5. 5

    Changing a 9-character password from lowercase only (26 symbols) to letters + digits (62 symbols) multiplies the number of possible passwords by about how much? Round to the nearest whole number.

  6. 6

    In Python, what does print(-4 // -6) show? (// is floor division)

  7. 7

    Binary search is used on 1 million sorted records. In the worst case, how many items must it check?

  8. 8

    Tower of Hanoi with 10 disks: what is the fewest moves needed to move the whole tower?

  9. 9

    What is the fewest bits needed to give each of 50 US states its own unique binary ID?

  10. 10

    Tower of Hanoi with 14 disks: what is the fewest moves needed to move the whole tower?

  11. 11

    An attacker can try 1 million passwords per second. A password is 6 lowercase letters (26 options each). How many hours to try every possibility? Give 1 decimal place.

  12. 12

    Binary search is used on 1 billion sorted records. In the worst case, how many items must it check?

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Teacher's comments

Free printable worksheets with answer keys · aethelsystems.com/worksheets/computer/12/challenge_cs_senior

Answer key (click to show)
  1. 1.58.0
  2. 2.14
  3. 3.33
  4. 4.2.2
  5. 5.2493
  6. 6.0
  7. 7.20
  8. 8.1023
  9. 9.6
  10. 10.16383
  11. 11.0.1
  12. 12.30

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