abs() and round() in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the absolute value of -7.

Python

result = [1](-7)
print(result)

Drag options to blanks, or click blank then click option'

Astr

Bround

Cint

Dabs

Attempts:

3 left

💡 Hint

Common Mistakes

Using round() instead of abs() will not remove the minus sign.

Using int() or str() won't change the sign of the number.

The abs() function returns the absolute value of a number, which means it makes negative numbers positive.

2fill in blank

medium

Complete the code to round the number 3.14159 to 2 decimal places.

Python

result = round(3.14159, [1])
print(result)

Drag options to blanks, or click blank then click option'

A2

B1

C3

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 0 will round to the nearest whole number.

Using 1 or 3 will round to the wrong number of decimals.

The round() function rounds a number to the specified number of decimal places. Here, 2 means two digits after the decimal point.

3fill in blank

hard

Fix the error in the code to correctly round the number 5.6789 without decimals.

Python

result = round([1])
print(result)

Drag options to blanks, or click blank then click option'

Around(5.6789)

B'5.6789'

C5.6789

Dint(5.6789)

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string instead of a number causes an error.

Calling round() inside round() is incorrect.

The round() function needs a number as input, not a string or another function call inside.

4fill in blank

hard

Fill both blanks to create a dictionary with words as keys and their absolute length difference from 4 as values.

Python

words = ['cat', 'house', 'dog', 'tree']
length_diff = {word: abs(len(word) [1] 4) for word in words if len(word) [2] 2}
print(length_diff)

Drag options to blanks, or click blank then click option'

A-

B+

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' instead of '-' changes the meaning.

Using '<' instead of '>' filters the wrong words.

The code calculates the absolute difference between the length of each word and 4, but only for words longer than 2 characters.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase words as keys, their rounded lengths as values, only if length is greater than 3.

Python

words = ['apple', 'bat', 'carrot', 'dog']
result = { [1]: round(len(word), [2]) for word in words if len(word) [3] 3 }
print(result)

Drag options to blanks, or click blank then click option'

Aword.upper()

B1

C>

Dword.lower()

Attempts:

3 left

💡 Hint

Common Mistakes

Using word.lower() instead of uppercase keys.

Using '<' instead of '>' filters wrong words.

Rounding to 0 decimals changes output meaning.

The dictionary keys are uppercase words, values are lengths rounded to 1 decimal (though lengths are integers), and only words longer than 3 are included.

Practice

1. What does the Python function abs() do when given a number?

easy

A. Rounds the number to the nearest integer

B. Returns the negative of the number

C. Converts the number to a string

D. Returns the positive distance of the number from zero

Solution

1. Step 1: Understand the purpose of abs()

   The abs() function returns how far a number is from zero without considering its sign.

2. Step 2: Compare with other options

   Rounding, string conversion, or negation are different functions; only abs() returns the positive distance.

3. Final Answer:

   Returns the positive distance of the number from zero -> Option D

4. Quick Check:

   abs(-5) = 5 [OK]

Hint: Think: absolute means distance without sign [OK]

Common Mistakes:

• Confusing abs() with round()
• Thinking abs() changes the number's sign
• Assuming abs() converts to string

2. Which of the following is the correct way to round the number 3.14159 to 2 decimal places in Python?

easy

A. round(3.14159, '2')

B. round(3.14159.2)

C. round(3.14159, 2)

D. round(3.14159, 2.0)

Solution

1. Step 1: Check the syntax of round()

   The round() function takes a number and an integer for decimal places, like round(number, digits).

2. Step 2: Validate each option

   round(3.14159, 2) uses correct syntax with an integer 2. round(3.14159.2) has a dot instead of a comma. round(3.14159, '2') uses a string '2' which is invalid. round(3.14159, 2.0) uses a float 2.0 which is accepted as decimal places.

3. Final Answer:

   round(3.14159, 2) -> Option C

4. Quick Check:

   round(3.14159, 2) = 3.14 [OK]

Hint: Use comma and integer for decimals in round() [OK]

Common Mistakes:

• Using dot instead of comma between arguments
• Passing decimal places as string
• Passing decimal places as float

3. What is the output of this code?

print(abs(-7.8))
print(round(2.675, 2))

medium

A. 7.8 and 2.68

B. 7.8 and 2.67

C. -7.8 and 2.68

D. -7.8 and 2.67

Solution

1. Step 1: Calculate abs(-7.8)

   The absolute value of -7.8 is 7.8, so the first print outputs 7.8.

2. Step 2: Calculate round(2.675, 2)

   Due to floating-point rounding, 2.675 rounds to 2.67 (not 2.68) in Python.

3. Final Answer:

   7.8 and 2.67 -> Option B

4. Quick Check:

   abs(-7.8) = 7.8, round(2.675, 2) = 2.67 [OK]

Hint: Remember floating-point quirks in round() [OK]

Common Mistakes:

• Expecting round(2.675, 2) to be 2.68
• Forgetting abs() returns positive value
• Mixing signs in output

4. The following code has an error. What is it?

num = -4.5
print(round(abs(num), 1.0))

medium

A. round() decimal places must be an integer, not float

B. abs() cannot take negative numbers

C. print() syntax is incorrect

D. num variable is not defined

Solution

1. Step 1: Analyze abs(num)

   The abs() function works fine with negative numbers, so no error here.

2. Step 2: Check round() arguments

   The second argument to round() must be an integer, but 1.0 is a float, causing a TypeError.

3. Final Answer:

   round() decimal places must be an integer, not float -> Option A

4. Quick Check:

   round(..., 1.0) causes error [OK]

Hint: Decimal places in round() must be int, not float [OK]

Common Mistakes:

• Thinking abs() can't take negatives
• Passing float instead of int for decimals
• Assuming print() syntax error

5. You have a list of numbers: nums = [-3.1415, 2.718, -1.414, 0]. You want to create a new list with the absolute values rounded to 2 decimal places. Which code does this correctly?

hard

A. rounded = [round(abs(x), 2) for x in nums]

B. rounded = [round(x, 2) for x in nums]

C. rounded = [round(abs(x), '2') for x in nums]

D. rounded = [round(abs(x), 2.0) for x in nums]

Solution

1. Step 1: Understand the goal

   We want absolute values first, then round them to 2 decimals.

2. Step 2: Check each option

   rounded = [round(abs(x), 2) for x in nums] correctly applies abs() then round() with integer 2. rounded = [round(x, 2) for x in nums] rounds but does not apply abs(), leaving negative values negative. rounded = [round(abs(x), '2') for x in nums] uses string '2' which is invalid. rounded = [round(abs(x), 2.0) for x in nums] uses float 2.0 which is accepted as decimal places.

3. Final Answer:

   rounded = [round(abs(x), 2) for x in nums] -> Option A

4. Quick Check:

   abs then round with int decimals [OK]

Hint: Apply abs() before round() with integer decimals [OK]

Common Mistakes:

• Rounding before abs() changes results
• Using string or float for decimal places
• Confusing order of functions