Binary number system in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to convert the decimal number 5 to binary using the built-in function.

Intro to Computing

binary_value = bin([1])

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

A8

B10

C2

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a binary number instead of a decimal number inside bin()

Confusing the base of the number

The bin() function converts a decimal number to its binary representation. Here, 5 is the decimal number to convert.

2fill in blank

medium

Complete the code to convert the binary string '1010' to a decimal number.

Intro to Computing

decimal_value = int('[1]', 2)

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

A1010

B10

C2

D1001

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a decimal number instead of a string

Forgetting to specify base 2

The int() function converts a string in a given base to a decimal integer. Here, '1010' is the binary string to convert.

3fill in blank

hard

Fix the error in the code to correctly convert the decimal number 12 to binary without the '0b' prefix.

Intro to Computing

binary_str = bin(12)[1]

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

A[1:]

B[2:]

C.substring(2)

D.slice(2)

Attempts:

3 left

💡 Hint

Common Mistakes

Using JavaScript string methods like .slice() or .substring() in Python

Using incorrect slicing syntax

The bin() function returns a string starting with '0b'. Using slicing [2:] removes the first two characters.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps decimal numbers 1 to 5 to their binary strings without the '0b' prefix.

Intro to Computing

binary_dict = {num: bin(num)[1] for num in range(1, 6) if num [2] 3}

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

A[2:]

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect slicing syntax

Using wrong comparison operators

The slicing [2:] removes the '0b' prefix from the binary string. The condition num > 3 filters numbers greater than 3.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase hexadecimal digits to their decimal values, including only digits greater than 9.

Intro to Computing

hex_dict = { [1]: int([2], 16) for [3] in ['A', 'B', 'C', 'D', 'E', 'F'] if int([3], 16) > 9 }

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

Adigit

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently

Forgetting to specify base 16 in int()

We use digit as the variable name for keys and values. The comprehension iterates over the list of hex digits and converts each to decimal using int(digit, 16). The condition filters digits with decimal value greater than 9.

Practice

1. What digits are used in the binary number system?

easy

A. Digits 1 to 10

B. Digits 0 to 9

C. Digits 0 to 7

D. Only 0 and 1

Solution

1. Step 1: Understand the binary system basics

   The binary number system uses only two digits to represent all numbers.

2. Step 2: Identify the digits used

   These digits are 0 and 1, representing off and on states in computers.

3. Final Answer:

   Only 0 and 1 -> Option D

4. Quick Check:

   Binary digits = 0 and 1 [OK]

Hint: Binary uses just two digits: 0 and 1 [OK]

Common Mistakes:

• Confusing binary with decimal digits
• Thinking binary uses digits 0 to 9
• Assuming binary includes digits beyond 1

2. Which of the following is the correct binary number?

easy

A. 1101

B. 1234

C. 1021

D. 2010

Solution

1. Step 1: Check each digit for binary validity

   Binary numbers only contain 0s and 1s. Check each option's digits.

2. Step 2: Identify the valid binary number

   1101 is 1101, which contains only 1s and 0s. Others have digits like 2 or 3, invalid in binary.

3. Final Answer:

   1101 -> Option A

4. Quick Check:

   Valid binary = digits 0 or 1 only [OK]

Hint: Binary digits are only 0 or 1, no other digits allowed [OK]

Common Mistakes:

• Choosing numbers with digits other than 0 or 1
• Confusing binary with decimal or octal numbers
• Ignoring invalid digits in options

3. What is the decimal value of the binary number 1011?

medium

A. 7

B. 11

C. 13

D. 9

Solution

1. Step 1: Assign powers of 2 to each bit

   From right to left, bits represent 2^0=1, 2^1=2, 2^2=4, 2^3=8.

2. Step 2: Calculate decimal value by adding bits with 1

   Bits: 1(8) + 0(4) + 1(2) + 1(1) = 8 + 0 + 2 + 1 = 11.

3. Final Answer:

   11 -> Option B

4. Quick Check:

   Binary 1011 = Decimal 11 [OK]

Hint: Add powers of 2 where bit is 1, starting from right [OK]

Common Mistakes:

• Misaligning bit positions and powers of 2
• Adding all bits instead of weighted values
• Confusing binary digits with decimal digits

4. Identify the error in this binary number: 11012

medium

A. Binary numbers cannot start with 1

B. Too many digits for a binary number

C. Contains digit '2' which is invalid in binary

D. Missing leading zeros

Solution

1. Step 1: Check each digit for binary validity

   Binary digits must be only 0 or 1. The digit '2' is not allowed.

2. Step 2: Confirm the invalid digit

   The presence of '2' makes the number invalid as a binary number.

3. Final Answer:

   Contains digit '2' which is invalid in binary -> Option C

4. Quick Check:

   Binary digits = 0 or 1 only [OK]

Hint: Binary digits never include 2 or higher [OK]

Common Mistakes:

• Thinking binary numbers have digit limits on length
• Believing binary cannot start with 1
• Assuming missing zeros is an error

5. Convert the decimal number 18 to binary.

hard

A. 10010

B. 11001

C. 10110

D. 10001

Solution

1. Step 1: Divide decimal number by 2 repeatedly

   18 ÷ 2 = 9 remainder 0; 9 ÷ 2 = 4 remainder 1; 4 ÷ 2 = 2 remainder 0; 2 ÷ 2 = 1 remainder 0; 1 ÷ 2 = 0 remainder 1.

2. Step 2: Write remainders in reverse order

   Reading remainders from last to first: 1 0 0 1 0.

3. Final Answer:

   10010 -> Option A

4. Quick Check:

   Decimal 18 = Binary 10010 [OK]

Hint: Divide by 2, collect remainders backward [OK]

Common Mistakes:

• Reading remainders in wrong order
• Mixing up division and subtraction steps
• Confusing binary digits with decimal digits