Math-related operations in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the abs() function do in Python?

The abs() function returns the absolute value of a number, which means it removes any negative sign and gives the distance from zero.

beginner

How do you calculate the power of a number in Python?

You can use the ** operator or the pow() function. For example, 2 ** 3 or pow(2, 3) both give 8.

intermediate

What is the difference between // and / operators in Python?

/ does normal division and returns a float. // does floor division and returns the largest whole number less than or equal to the result.

beginner

How can you get the remainder of a division in Python?

Use the modulo operator %. For example, 7 % 3 gives 1 because 7 divided by 3 leaves a remainder of 1.

beginner

What does the round() function do?

The round() function rounds a floating-point number to the nearest whole number or to a specified number of decimal places.

What is the output of abs(-10) in Python?

A -10

B 0

C 10

D Error

abs() returns the positive value of a number, so abs(-10) is 10.

Which operator gives the remainder of a division?

A %

B //

C /

D **

The modulo operator % returns the remainder after division.

What does 5 // 2 return?

A 2

B 3

C 2.5

D 1

// is floor division, so 5 // 2 returns 2.

How do you calculate 3 to the power of 4 in Python?

A 3 ^ 4

B 3 ** 4

C pow(4, 3)

D 3 % 4

The power operator is **, so 3 ** 4 calculates 3 to the power of 4.

What does round(3.14159, 2) return?

A 3.15

B 3.1

C 3

D 3.14

round() rounds to the specified decimal places, so rounding to 2 decimals gives 3.14.

Explain how to perform division and get both the quotient and remainder in Python.

Think about how to get the whole number part and the leftover part separately.

Describe how to use Python functions and operators to calculate powers and absolute values.

Remember the symbols and function names that help with these math operations.

Practice

1. Which operator in Python is used to find the remainder of a division?

easy

A. The multiplication operator *

B. The division operator /

C. The exponent operator **

D. The modulus operator %

Solution

1. Step 1: Understand the modulus operator

   The modulus operator % returns the remainder after division of one number by another.

2. Step 2: Compare with other operators

   The division operator / returns the quotient, exponent ** raises to power, and multiplication * multiplies numbers.

3. Final Answer:

   The modulus operator % -> Option D

4. Quick Check:

   Remainder = % operator [OK]

Hint: Remainder uses % operator in math [OK]

Common Mistakes:

• Confusing / with %
• Using * for remainder
• Thinking ** gives remainder

2. Which of the following is the correct operator syntax to calculate 3 to the power of 4 in Python?

easy

A. 3 ^ 4

B. 3 ^^ 4

C. 3 ** 4

D. pow(3, 4)

Solution

1. Step 1: Identify the exponent operator in Python

   Python uses ** to calculate powers, so 3 ** 4 means 3 to the power 4.

2. Step 2: Check other options

   3 ^ 4 is bitwise XOR, pow(3, 4) is a function but not syntax operator, 3 ^^ 4 is invalid syntax.

3. Final Answer:

   3 ** 4 -> Option C

4. Quick Check:

   Power uses ** operator [OK]

Hint: Use ** for powers, not ^ [OK]

Common Mistakes:

• Using ^ instead of **
• Trying ^^ which is invalid
• Confusing pow() function with operator

3. What is the output of this Python code?

result = 10 % 3
print(result)

medium

A. 1

B. 3

C. 0

D. 10

Solution

1. Step 1: Calculate 10 modulo 3

   10 divided by 3 is 3 with remainder 1, so 10 % 3 equals 1.

2. Step 2: Understand print output

   The print statement outputs the value stored in result, which is 1.

3. Final Answer:

   1 -> Option A

4. Quick Check:

   10 % 3 = 1 [OK]

Hint: Modulo gives remainder after division [OK]

Common Mistakes:

• Confusing modulo with division
• Expecting quotient instead of remainder
• Misreading print output

4. Find the error in this code snippet:

value = 5 **
print(value)

medium

A. print() function is used incorrectly

B. Missing second operand for exponent operator

C. Exponent operator should be ^

D. Variable name 'value' is invalid

Solution

1. Step 1: Check the exponent operator usage

   The exponent operator ** needs two numbers, but here only one number (5) is given before it.

2. Step 2: Identify syntax error

   Because the second operand is missing, Python will raise a syntax error before print runs.

3. Final Answer:

   Missing second operand for exponent operator -> Option B

4. Quick Check:

   ** needs two numbers [OK]

Hint: Exponent needs two numbers, not one [OK]

Common Mistakes:

• Using ^ instead of **
• Thinking print() is wrong here
• Assuming variable name causes error

5. You want to calculate the area of a circle with radius 7 using Python. Which code correctly uses math operations to do this?

import math
radius = 7
area = ?
print(area)

hard

A. area = math.pi * (radius ** 2)

B. area = math.pi ** radius

C. area = pi * radius * radius

D. area = math.pi + radius ** 2

Solution

1. Step 1: Recall formula for circle area

   The area of a circle is π times radius squared, or π * r².

2. Step 2: Translate formula to Python code

   Use math.pi for π and radius ** 2 for radius squared, so math.pi * (radius ** 2).

3. Final Answer:

   area = math.pi * (radius ** 2) -> Option A

4. Quick Check:

   Area = π * r² [OK]

Hint: Use ** 2 for square, multiply by math.pi [OK]

Common Mistakes:

• Using addition instead of multiplication
• Using exponent on pi instead of radius
• Forgetting to square radius