Int, Long, Float, Double number types in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an integer variable named age with value 30.

Kotlin

val age: Int = [1]

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

A30.0

B30L

C30.0f

D30

Attempts:

3 left

💡 Hint

Common Mistakes

Using 30L which is a Long type suffix.

Using 30.0f or 30.0 which are floating point numbers.

The Int type holds whole numbers without decimals. So 30 is correct.

2fill in blank

medium

Complete the code to declare a Long variable named distance with value 10000000000.

Kotlin

val distance: Long = [1]

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

A10000000000

B10000000000L

C10000000000f

D10000000000.0

Attempts:

3 left

💡 Hint

Common Mistakes

Not adding L suffix causes errors or wrong type.

Using floating point suffixes like f or decimals.

The Long type holds large whole numbers. Adding L suffix tells Kotlin it's a Long.

3fill in blank

hard

Fix the error in the code by choosing the correct value for a Float variable temperature.

Kotlin

val temperature: Float = [1]

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

A36.6f

B36.6

C36

D36L

Attempts:

3 left

💡 Hint

Common Mistakes

Using a decimal without f suffix causes type mismatch.

Using integer or Long values for Float variables.

Float values require the f suffix in Kotlin to distinguish from Double.

4fill in blank

hard

Fill both blanks to create a Double variable price with value 19.99 and print it.

Kotlin

val price: [1] = 19.99
println([2])

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

ADouble

Bprice

CFloat

Dcost

Attempts:

3 left

💡 Hint

Common Mistakes

Using Float instead of Double for decimal literals without suffix.

Printing a variable name that was not declared.

price is declared as Double type and printed by its name price.

5fill in blank

hard

Fill all three blanks to create a map of numbers with their types as strings, filtering only those with value greater than 10.

Kotlin

val numbers = mapOf(
  [1] to "Int",
  [2] to "Long",
  [3] to "Float"
).filter { it.key > 10 }

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

A15

B20L

C12.5f

D8

Attempts:

3 left

💡 Hint

Common Mistakes

Using suffixes incorrectly or mixing types.

Including numbers less than or equal to 10 which get filtered out.

We use 15 as Int, 20L as Long, and 12.5f as Float. The filter keeps only keys greater than 10.

Practice

1. Which Kotlin number type should you use to store a whole number like 42?

easy

A. Float

B. Double

C. Int

D. Long

Solution

1. Step 1: Understand the number type categories

   Int is used for normal whole numbers without decimals.

2. Step 2: Match the number 42 to the type

   42 is a whole number and fits in Int range.

3. Final Answer:

   Int -> Option C

4. Quick Check:

   Whole number 42 = Int [OK]

Hint: Whole numbers without decimals use Int by default [OK]

Common Mistakes:

• Choosing Float or Double for whole numbers
• Using Long unnecessarily for small numbers

2. Which of the following is the correct way to declare a Float variable with value 3.14 in Kotlin?

easy

A. val pi: Float = 3.14

B. val pi: Float = 3.14Ff

C. val pi: Float = 3.14d

D. val pi: Float = 3.14f

Solution

1. Step 1: Recall Kotlin Float literal syntax

   Float literals require an 'f' or 'F' suffix to distinguish from Double.

2. Step 2: Check each option

   val pi: Float = 3.14f uses '3.14f' which is correct. val pi: Float = 3.14 misses the suffix. val pi: Float = 3.14Ff has invalid suffix 'Ff'. val pi: Float = 3.14d uses 'd' which is for Double.

3. Final Answer:

   val pi: Float = 3.14f -> Option D

4. Quick Check:

   Float literals end with 'f' [OK]

Hint: Add 'f' suffix to decimal for Float type [OK]

Common Mistakes:

• Omitting 'f' suffix for Float literals
• Using 'd' suffix which is for Double
• Using invalid suffixes like 'Ff'

3. What will be the output of this Kotlin code?

val a: Int = 100000
val b: Long = 10000000000L
val c: Float = 3.14f
val d: Double = 3.1415926535
println("$a $b $c $d")

medium

A. 100000 10000000000 3.1400001 3.1415926535

B. 100000 10000000000 3.14 3.1415926535

C. 100000 10000000000 3.14f 3.1415926535

D. 100000 10000000000 3.14 3.1415927

Solution

1. Step 1: Understand variable types and precision

   a is Int (100000), b is Long (10000000000L), c is Float (3.14f), d is Double (3.1415926535).

2. Step 2: Check printed values and precision

   Float prints as 3.1400001 due to precision limits, Double prints full precision (3.1415926535). So output matches 100000 10000000000 3.1400001 3.1415926535.

3. Final Answer:

   100000 10000000000 3.1400001 3.1415926535 -> Option A

4. Quick Check:

   Float prints with slight precision difference [OK]

Hint: Float prints decimals with limited precision [OK]

Common Mistakes:

• Thinking Float prints exactly 3.14
• Confusing Float and Double precision
• Misreading Long large number formatting

4. Identify the error in this Kotlin code snippet:

val bigNumber: Long = 12345678901234567890
val smallNumber: Int = 2147483648

medium

A. Both numbers are too large for their types

B. Only bigNumber is too large for Long

C. No errors, code is correct

D. Only smallNumber is too large for Int

Solution

1. Step 1: Check Long value range

   Long can hold values up to 9,223,372,036,854,775,807. The bigNumber literal exceeds this, so it causes an error.

2. Step 2: Check Int value range

   Int max is 2,147,483,647. The smallNumber is 2,147,483,648 which is 1 more than max, so it causes an error.

3. Step 3: Analyze the code

   Both literals are too large for their types, causing compile errors.

4. Final Answer:

   Both numbers are too large for their types -> Option A

5. Quick Check:

   Int max 2147483647, Long max 9223372036854775807; both exceeded [OK]

Hint: Check max values: Int max 2,147,483,647; Long max 9,223,372,036,854,775,807 [OK]

Common Mistakes:

• Ignoring suffix 'L' for Long literals
• Assuming Long can hold any big number
• Not checking Int max value

5. You want to store the population of a country which is about 1.4 billion people. Which Kotlin type is best and why?

Options:
A) Long because it can store very large whole numbers
B) Int because it stores whole numbers
C) Float because it stores decimal numbers
D) Double because it stores decimal numbers with more precision

hard

A. Int because it stores whole numbers

B. Long because it can store very large whole numbers

C. Float because it stores decimal numbers

D. Double because it stores decimal numbers with more precision

Solution

1. Step 1: Understand the population size and type limits

   Population is about 1.4 billion (1,400,000,000). Int max is 2,147,483,647, so Int can hold it.

2. Step 2: Consider best practice for large numbers

   Though Int can hold 1.4 billion, Long is safer for very large whole numbers and future growth.

3. Step 3: Decide on the best type

   Long is best because it can store very large whole numbers beyond Int range.

4. Final Answer:

   Long because it can store very large whole numbers -> Option B

5. Quick Check:

   Long preferred for large integers like population [OK]

Hint: Use Long for very large whole numbers like population [OK]

Common Mistakes:

• Choosing Int without considering future growth
• Using Float or Double for whole numbers unnecessarily
• Ignoring future growth beyond Int range