Arithmetic operators in Kotlin - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Kotlin code?

Consider the following Kotlin code snippet. What will it print when run?

Kotlin

fun main() {
    val a = 10
    val b = 3
    println(a / b)
}

A 3

B 3.3333333

C 3.0

D 4

💡 Hint

Remember that dividing two integers in Kotlin results in an integer division.

In Kotlin, dividing two Int values uses integer division, so 10 / 3 equals 3, discarding the remainder.

❓ Predict Output

intermediate

What is the output of this Kotlin code with mixed types?

What will this Kotlin program print?

Kotlin

fun main() {
    val x = 7
    val y = 2.0
    println(x / y)
}

A 3

B 3.50

C 3.0

D 3.5

💡 Hint

When dividing an Int by a Double, Kotlin promotes the Int to Double.

Since 'y' is a Double, 'x' is converted to Double and floating-point division is performed, resulting in 3.5.

❓ Predict Output

advanced

What is the output of this Kotlin code using the modulus operator?

Analyze the following Kotlin code and select the output it produces.

Kotlin

fun main() {
    val a = 17
    val b = 5
    println(a % b)
}

A 1

B 3

C 2

D 0

💡 Hint

The modulus operator (%) gives the remainder after division.

17 divided by 5 is 3 with a remainder of 2, so 17 % 5 equals 2.

❓ Predict Output

advanced

What is the output of this Kotlin code with mixed arithmetic and assignment?

What will be printed by this Kotlin program?

Kotlin

fun main() {
    var n = 8
    n += 3 * 2
    println(n)
}

A 14

B 16

C 22

D 11

💡 Hint

Remember the order of operations: multiplication before addition.

3 * 2 equals 6, then n += 6 means n = 8 + 6 = 14.

❓ Predict Output

expert

What is the output of this Kotlin code with integer overflow?

Consider this Kotlin code snippet. What will it print?

Kotlin

fun main() {
    val maxInt = Int.MAX_VALUE
    val result = maxInt + 1
    println(result)
}

A OverflowException

B -2147483648

C 2147483647

D 2147483648

💡 Hint

Adding 1 to Int.MAX_VALUE causes integer overflow in Kotlin's Int type.

Kotlin's Int type is a 32-bit signed integer. Adding 1 to the maximum value wraps around to the minimum value (-2147483648).

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