Tracing loop output: Class 11 practice
range(a, b, k) produces a, a + k, … stopping before b. Read the method, follow the three worked examples, then try the six questions.
What you should know first
- Variables and assignment
The idea behind tracing loop output
range(a, b, k) produces a, a + k, … stopping before b. To predict a loop's result, track the variables in a small table, one row per iteration.
Step-by-step method
- List the values range() produces.
- Update the variables for each value.
- Write the final value or printed output.
Worked example 1 (Basic)
What is printed? total = 0 for i in range(2, 10, 3): total += i print(total)
- range gives 2, 5, 8
- Sum = 15
- Answer: 15
Worked example 2 (Standard)
How many times is "hi" printed? for i in range(2, 14, 1): if i % 2 == 0: print("hi")
- Values: 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
- Even values: 2, 4, 6, 8, 10, 12
- Answer: 6
Worked example 3 (Challenge)
What is printed? f = 1 i = 1 while i <= 7: f = f * i i += 1 print(f)
- Multiplies 1 × 2 × … × 7
- = 5040
- Answer: 5040
Common mistakes and misconceptions
- Including the stop value of range
- Forgetting to update an accumulator
Practice questions
- (Basic) What is printed? total = 0 for i in range(1, 17, 1): total += i print(total)
- (Basic) What is printed? total = 0 for i in range(5, 14, 3): total += i print(total)
- (Standard) How many times is "hi" printed? for i in range(5, 10, 1): if i % 2 == 0: print("hi")
- (Standard) How many times is "hi" printed? for i in range(1, 16, 1): if i % 2 == 0: print("hi")
- (Challenge) What is printed? f = 1 i = 1 while i <= 3: f = f * i i += 1 print(f)
- (Challenge) What is printed? f = 1 i = 1 while i <= 6: f = f * i i += 1 print(f)
Answer key with full working
- Q1: range gives 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 → Sum = 136 → Answer: 136
- Q2: range gives 5, 8, 11 → Sum = 24 → Answer: 24
- Q3: Values: 5, 6, 7, 8, 9 → Even values: 6, 8 → Answer: 2
- Q4: Values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 → Even values: 2, 4, 6, 8, 10, 12, 14 → Answer: 7
- Q5: Multiplies 1 × 2 × … × 3 → = 6 → Answer: 6
- Q6: Multiplies 1 × 2 × … × 6 → = 720 → Answer: 720
Syllabus note
This skill is listed under "Flow of Control" for Class 11 in the NCERT/CBSE books. ICSE, IGCSE, IB and state boards may teach it in a different chapter or year.
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.
Related practice and notes
Frequently asked questions
Which chapter is tracing loop output in?
"Flow of Control", Class 11 Computer Science (NCERT/CBSE). Other boards may place it differently.
How were the answers checked?
Answers on this page are generated and automatically re-checked by a second, independent calculation. They have not been reviewed by a teacher — if you spot a problem, tell us on WhatsApp.