Arithmetic operators in C Sharp (C#) - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of mixed arithmetic operations

What is the output of the following C# code?

C Sharp (C#)

int a = 10;
int b = 3;
int result = a / b * b + a % b;
Console.WriteLine(result);

A 10

B 9

C 12

D 3

💡 Hint

Remember integer division truncates the decimal part.

Integer division 10 / 3 equals 3, then 3 * 3 = 9, plus remainder 10 % 3 = 1, total 10.

❓ Predict Output

intermediate

Result of floating-point arithmetic

What will be printed by this C# code snippet?

C Sharp (C#)

double x = 5.0 / 2.0;
Console.WriteLine(x);

A 2

B 3

C 2.0

D 2.5

💡 Hint

Division with doubles keeps the decimal part.

Dividing 5.0 by 2.0 results in 2.5 as a double value.

❓ Predict Output

advanced

Understanding operator precedence

What is the output of this C# code?

C Sharp (C#)

int a = 4;
int b = 2;
int c = 3;
int result = a + b * c - b / c;
Console.WriteLine(result);

A 8

B 10

C 9

D 7

💡 Hint

Remember multiplication and division have higher precedence than addition and subtraction.

b * c = 2 * 3 = 6; b / c = 2 / 3 = 0 (integer division); so result = 4 + 6 - 0 = 10.

❓ Predict Output

advanced

Effect of parentheses on arithmetic operations

What will this C# code print?

C Sharp (C#)

int x = 8;
int y = 4;
int z = 2;
int result = (x + y) / z;
Console.WriteLine(result);

A 7

B 14

C 3

D 6

💡 Hint

Parentheses change the order of operations.

Parentheses cause x + y to be evaluated first: 8 + 4 = 12; then 12 / 2 = 6.

❓ Predict Output

expert

Complex arithmetic with mixed types

What is the output of this C# code?

C Sharp (C#)

int a = 7;
double b = 2.5;
var result = a / b + a % (int)b;
Console.WriteLine(result);

A 5.0

B 4.8

C 3.8

D 5.3

💡 Hint

Remember that % requires integers and division with double returns double.

a / b = 7 / 2.5 = 2.8; a % (int)b = 7 % 2 = 1; sum = 2.8 + 1 = 3.8.

Practice

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

easy

A. -

B. /

C. *

D. %

Solution

1. Step 1: Understand the purpose of each operator

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

2. Step 2: Identify the operator for remainder

   The operator that gives the remainder is %.

3. Final Answer:

   % -> Option D

4. Quick Check:

   Remainder operator = % [OK]

Hint: Remainder uses % symbol, like dividing candies leftover [OK]

Common Mistakes:

• Confusing / (division) with % (remainder)
• Using * or - instead of %
• Thinking % is modulus function

2. Which of the following is the correct syntax to multiply two integers a and b in C#?

easy

A. int result = a + b;

B. int result = a * b;

C. int result = a & b;

D. int result = a x b;

Solution

1. Step 1: Recall multiplication operator in C#

   Multiplication uses the asterisk symbol * between operands.

2. Step 2: Check each option's syntax

   int result = a * b; uses * correctly. int result = a x b; uses x which is invalid. int result = a & b; uses & which is bitwise AND, not multiplication. int result = a + b; uses + which is addition.

3. Final Answer:

   int result = a * b; -> Option B

4. Quick Check:

   Multiplication operator = * [OK]

Hint: Use * for multiply, not x or & [OK]

Common Mistakes:

• Using x instead of *
• Using & thinking it's multiply
• Confusing + with *

3. What is the output of the following C# code?

int a = 7;
int b = 3;
Console.WriteLine(a / b);

medium

A. 2

B. 2.3333333

C. 3

D. 1

Solution

1. Step 1: Understand integer division in C#

   Both a and b are integers, so division a / b performs integer division, dropping decimals.

2. Step 2: Calculate integer division result

   7 divided by 3 is 2.333..., but integer division truncates to 2.

3. Final Answer:

   2 -> Option A

4. Quick Check:

   Integer division truncates decimals = 2 [OK]

Hint: Integer division drops decimals, so 7/3 = 2 [OK]

Common Mistakes:

• Expecting decimal result
• Confusing integer division with float division
• Using wrong operator

4. Identify the error in this C# code snippet:

int x = 10;
int y = 0;
int z = x / y;
Console.WriteLine(z);

medium

A. Variable z is not declared

B. Missing semicolon after Console.WriteLine

C. Division by zero causes runtime error

D. x and y must be floats for division

Solution

1. Step 1: Analyze division operation

   The code divides x by y, where y is zero.

2. Step 2: Understand division by zero in C#

   Dividing an integer by zero causes a runtime error (DivideByZeroException).

3. Final Answer:

   Division by zero causes runtime error -> Option C

4. Quick Check:

   Division by zero throws error [OK]

Hint: Never divide by zero; it crashes your program [OK]

Common Mistakes:

• Ignoring division by zero error
• Thinking missing semicolon causes error
• Assuming float needed for division

5. You want to calculate the average of two integers a and b in C#. Which expression correctly computes the average as a floating-point number?

hard

A. (a + b) / 2.0

B. (a + b) / 2

C. a / 2 + b / 2

D. (float)((a + b) / 2)

Solution

1. Step 1: Understand integer vs floating-point division

   Using only integers causes integer division, dropping decimals.

2. Step 2: Check each option for floating-point division

   (a + b) / 2 divides integers, result is integer. (a + b) / 2.0 divides by 2.0 (double), so result is floating-point. a / 2 + b / 2 divides separately then adds, but integer division truncates each part. (float)((a + b) / 2) first performs integer division (a + b) / 2 truncating to integer, then casts to float, resulting in incorrect average due to truncation.

3. Final Answer:

   (a + b) / 2.0 -> Option A

4. Quick Check:

   Divide by 2.0 for float average [OK]

Hint: Divide by 2.0 (double) to get float average, not int [OK]

Common Mistakes:

• Using integer division dropping decimals
• Adding halves separately causing truncation
• Casting after division instead of before