Arithmetic operators in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are arithmetic operators in Kotlin?

Arithmetic operators are symbols that perform basic math operations like addition, subtraction, multiplication, division, and modulus on numbers.

beginner

What does the '+' operator do in Kotlin?

The '+' operator adds two numbers together. For example, 3 + 2 equals 5.

beginner

What is the result of 10 % 3 in Kotlin?

The '%' operator gives the remainder of division. 10 % 3 equals 1 because 3 goes into 10 three times with 1 left over.

intermediate

How does Kotlin handle division with '/' operator for integers?

When dividing two integers, Kotlin performs integer division, which means it returns the whole number part only, discarding any remainder.

beginner

What is the difference between '/' and '%' operators in Kotlin?

'/' divides two numbers and returns the quotient, while '%' returns the remainder after division.

What is the result of 7 + 5 in Kotlin?

A 2

B 12

C 75

D Error

7 + 5 adds the two numbers to get 12.

What does the '%' operator do?

A Returns the remainder of division

B Divides two numbers

C Multiplies two numbers

D Subtracts two numbers

The '%' operator returns the remainder after dividing two numbers.

What is the output of 10 / 4 in Kotlin when both are integers?

A 2

B 2.5

C 3

D 4

Integer division discards the decimal part, so 10 / 4 equals 2.

Which operator multiplies two numbers?

A +

B -

C /

D *

The '*' operator multiplies two numbers.

What is the result of 15 % 6?

A 2

B 0

C 3

D 9

15 divided by 6 is 2 with a remainder of 3, so 15 % 6 equals 3.

Explain the five basic arithmetic operators in Kotlin and give an example of each.

Think about +, -, *, /, and % symbols.

Describe how Kotlin handles division when both numbers are integers.

What happens to the decimal part?

Practice

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

easy

A. The / operator

B. The % operator

C. The * operator

D. The - operator

Solution

1. Step 1: Understand the meaning of each operator

   The % operator gives the remainder after division, / divides, * multiplies, and - subtracts.

2. Step 2: Identify the operator for remainder

   The % operator is specifically for remainder calculation in Kotlin.

3. Final Answer:

   The % operator -> Option B

4. Quick Check:

   Remainder operator = % [OK]

Hint: Remember % means remainder in math and Kotlin [OK]

Common Mistakes:

• Confusing / with %, thinking / gives remainder
• Using * or - for remainder
• Mixing up operators with similar symbols

2. Which of the following is the correct way to write a multiplication operation in Kotlin?

easy

A. val result = 5 x 3

B. val result = 5 . 3

C. val result = 5 / 3

D. val result = 5 * 3

Solution

1. Step 1: Recall Kotlin syntax for multiplication

   Kotlin uses * for multiplication, not x or dot.

2. Step 2: Check each option

   val result = 5 * 3 uses * correctly; others are invalid syntax or different operations.

3. Final Answer:

   val result = 5 * 3 -> Option D

4. Quick Check:

   Multiplication operator = * [OK]

Hint: Use * for multiplication, not x or dot [OK]

Common Mistakes:

• Using x instead of *
• Using dot for multiplication
• Confusing division / with multiplication

3. What is the output of the following Kotlin code?

val a = 10
val b = 3
println(a / b)

medium

A. 3

B. 3.3333333

C. 3.0

D. Error

Solution

1. Step 1: Identify variable types and operation

   a and b are integers, so a / b does integer division.

2. Step 2: Calculate integer division result

   10 divided by 3 is 3.333..., but integer division drops decimals, so result is 3.

3. Final Answer:

   3 -> Option A

4. Quick Check:

   Integer division drops decimals = 3 [OK]

Hint: Integer division drops decimals; result is integer [OK]

Common Mistakes:

• Expecting decimal result with integer division
• Confusing / with floating-point division
• Thinking output is 3.0 or error

4. The following Kotlin code has an error. What is the problem?

val x = 7
val y = 2
val result = x / y.toDouble()
println(result)

medium

A. Cannot call toDouble() on y

B. Division operator / cannot mix Int and Double

C. No error, code runs and prints 3.5

D. Missing explicit type declaration for result

Solution

1. Step 1: Analyze the types involved in division

   y.toDouble() converts y to Double, so x / y.toDouble() divides Int by Double.

2. Step 2: Check Kotlin's handling of mixed numeric types

   Kotlin automatically converts Int to Double for mixed operations, so no error occurs.

3. Final Answer:

   No error, code runs and prints 3.5 -> Option C

4. Quick Check:

   Mixed Int/Double division allowed = 3.5 [OK]

Hint: Kotlin auto-converts Int to Double in mixed division [OK]

Common Mistakes:

• Thinking toDouble() causes error
• Believing mixed types cause syntax error
• Expecting need for explicit type declaration

5. You want to calculate the average of three large integer scores (e.g., 1000000000 each) in Kotlin and get a precise decimal result. Which code snippet correctly does this?

hard

A. val avg = (score1.toDouble() + score2.toDouble() + score3.toDouble()) / 3

B. val avg = (score1 + score2 + score3) / 3.0

C. val avg = (score1 + score2 + score3).toDouble() / 3

D. val avg = (score1 + score2 + score3) / 3

Solution

1. Step 1: Understand integer division problem

   Dividing integers by integer 3 causes integer division, losing decimals.

2. Step 2: Convert all scores to Double before division

   Converting each score to Double ensures floating-point division and precise average.

3. Step 3: Check each option

   val avg = (score1.toDouble() + score2.toDouble() + score3.toDouble()) / 3 converts all scores to Double before adding and dividing, giving correct decimal average.

4. Final Answer:

   val avg = (score1.toDouble() + score2.toDouble() + score3.toDouble()) / 3 -> Option A

5. Quick Check:

   Convert all to Double before division for decimal average [OK]

Hint: Convert all integers to Double before dividing for decimals [OK]

Common Mistakes:

• Dividing integers directly causing integer division
• Converting sum to Double after integer division
• Converting only one score to Double