All Exams Test series for 1 year @ ₹349 only
Question

What is (1000000001) 2– (0.0101)­ 2equal to?

This question was previously asked in
NDA II 2015 GAT Previous Year Paper (16-Dec-2015)
The correct answer is

(512.6875) 10

Understanding the Binary Subtraction Problem

The question asks us to perform a subtraction between two binary numbers and then express the result in decimal (base 10). The two binary numbers are a large integer, (1000000001)2, and a fractional number, (0.0101)2.

To solve this, we first need to convert each binary number into its equivalent decimal representation. After obtaining the decimal values, we perform the subtraction and then identify the correct option.

Converting Binary Numbers to Decimal (Base 10)

Converting a binary number to decimal involves summing the products of each digit with the corresponding power of 2. For digits to the left of the binary point, the powers of 2 are non-negative (starting from \(2^0\)), and for digits to the right, they are negative (starting from \(2^{-1}\)).

Convert (1000000001)2 to Decimal

This number has 10 digits. We start from the rightmost digit (position 0) and move left.

\( (1000000001)_2 = 1 \times 2^9 + 0 \times 2^8 + 0 \times 2^7 + 0 \times 2^6 + 0 \times 2^5 + 0 \times 2^4 + 0 \times 2^3 + 0 \times 2^2 + 0 \times 2^1 + 1 \times 2^0 \)

Calculating the powers of 2:

  • \(2^9 = 512\)
  • \(2^0 = 1\)
  • Other powers of 2 multiplied by 0 are 0.

So, the decimal value is:

\( 512 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 0 + 1 = 513 \)

Thus, (1000000001)2 = 51310.

Convert (0.0101)2 to Decimal

This is a fractional binary number. We start from the first digit to the right of the binary point (position -1) and move right.

\( (0.0101)_2 = 0 \times 2^0 + 0 \times 2^{-1} + 1 \times 2^{-2} + 0 \times 2^{-3} + 1 \times 2^{-4} \)

Calculating the negative powers of 2:

  • \(2^{-1} = \frac{1}{2} = 0.5\)
  • \(2^{-2} = \frac{1}{4} = 0.25\)
  • \(2^{-3} = \frac{1}{8} = 0.125\)
  • \(2^{-4} = \frac{1}{16} = 0.0625\)

So, the decimal value is:

\( 0 \times 1 + 0 \times 0.5 + 1 \times 0.25 + 0 \times 0.125 + 1 \times 0.0625 \)

\( = 0 + 0 + 0.25 + 0 + 0.0625 = 0.3125 \)

Thus, (0.0101)2 = 0.312510.

Binary to Decimal Conversion Summary
Binary Number Conversion Calculation Decimal Equivalent
(1000000001)2 \(1 \times 2^9 + 1 \times 2^0\) 513
(0.0101)2 \(0 \times 2^{-1} + 1 \times 2^{-2} + 0 \times 2^{-3} + 1 \times 2^{-4}\) 0.3125

Performing the Subtraction in Decimal

Now that we have the decimal equivalents, we can perform the subtraction:

\( (1000000001)_2 - (0.0101)_2 = 513_{10} - 0.3125_{10} \)

Subtracting the decimal values:

\( 513.0000 - 0.3125 = 512.6875 \)

The result of the subtraction is 512.6875 in decimal.

Comparing with Options

Let's compare our calculated result with the given options:

  • Option 1: (512.6775) 10
  • Option 2: (512.6875) 10
  • Option 3: (512.6975) 10
  • Option 4: (512.0909) 10

Our calculated result, 512.6875, exactly matches Option 2.

Conclusion

By converting both binary numbers to their decimal equivalents and performing the subtraction, we found that (1000000001)2 – (0.0101)2 is equal to 512.6875 in base 10.

Revision Table: Binary Subtraction and Conversion

Key Steps for Binary Subtraction with Decimal Conversion
Step Description In this Problem
1 Convert the first binary number to decimal. (1000000001)2 → 51310
2 Convert the second binary number (including fractional part) to decimal. (0.0101)2 → 0.312510
3 Perform the subtraction using the decimal values. 513 - 0.3125 = 512.6875
4 Match the result with the given decimal options. 512.6875 matches Option 2.

Additional Information: Number Systems

Number systems are ways of representing numbers. Common number systems include:

  • Decimal System (Base 10): Uses digits 0-9. Each position represents a power of 10. This is the system we use daily.
  • Binary System (Base 2): Uses digits 0 and 1. Each position represents a power of 2. This system is fundamental in computing.
  • Octal System (Base 8): Uses digits 0-7. Each position represents a power of 8.
  • Hexadecimal System (Base 16): Uses digits 0-9 and letters A-F (A=10, B=11, ..., F=15). Each position represents a power of 16. Used in computing and digital electronics.

Converting between these systems is a key skill in digital electronics and computer science.

Fractional parts in any base work similarly: digits to the right of the radix point are multiplied by decreasing negative powers of the base.

Was this answer helpful?

Similar Questions

  1. What is (1110011) 2÷ (10111) 2equal to ?

  2. If x 3 + y 3= (100010111) 2and x + y = (11111) 2, then what is (x - y) + xy equal to ?

  3. The number (1101101 + 1011011) 2can be written in decimal system as

  4. A binary number is represented by (cdccddcccddd) 2, where c > d. What is its decimal equivalent?

  5. The sum of the binary numbers (11011) 2, (10110110)2 and (10011x0y) 2is the binary number (101101101) 2. What are the values of x and y?

  6. The remainder and quotient of the binary division (101110) 2by (110) 2are respectively

  7. In the binary equation (1p101) 2+ (10q1) 2= (100r00) 2

    Where p, q and r are binary digits, what are the possible values of p, q and r respectively?
  8. If the number 235 in decimal system is converted into binary system, then what is the resulting number?

  9. What is the binary equivalent of the decimal number 0.3125?

  10. The decimal number (127.25) 10, when converted to binary number, takes the form


Important Questions from Binary Operations

  1. Multiplication of 111 2by 101 2is

  2. Let * be binary operation defined on R by \(\rm p * q=\frac{p+q}{2}, \forall \) p, q ∈ R. The operation is:

  3. Convert 29 into binary.

    A. 10101

    B. 11110

    C. 11101

    D. 11001

  4. The product of the two binary numbers 011 and 110 is:

  5. If G is the set of integer numbers, and a.b = a – b, ∀ a, b ∈ G, then G is

Need Expert Advice?
Upcoming Exams
NDA
September 13, 2026
CDS
September 13, 2026
Test Series
NDA img
Defence
NDA 2026 Mock Test Series (Latest Pattern)
501 Tests 1 Tests Free
765 Attempts
4.7(129)
English, Hindi

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App