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

What are the last three digits in the multiplication of
\(4321012345 \times 98766789\)?

This question was previously asked in
CDS 2 2024 Maths Question Paper (01-Sep-2024)
The correct answer is
2, 0, 5

Finding the Last Three Digits of a Large Multiplication

The question asks for the last three digits of the product obtained when multiplying \(4321012345\) by \(98766789\). To find the last three digits of any number, we need to determine the remainder when that number is divided by \(1000\). This is also known as finding the number modulo \(1000\).

A key property of multiplication is that the last three digits of the product depend only on the last three digits of the numbers being multiplied. We can express this using modular arithmetic:

\((a \times b) \pmod{1000} = ((a \pmod{1000}) \times (b \pmod{1000})) \pmod{1000}\)

Step-by-Step Calculation

  1. Identify the last three digits of each number:

    • The last three digits of \(4321012345\) are \(345\). So, \(4321012345 \pmod{1000} = 345\).
    • The last three digits of \(98766789\) are \(789\). So, \(98766789 \pmod{1000} = 789\).
  2. Multiply these last three digits:

    We need to calculate the product of \(345\) and \(789\).

    \(345 \times 789\)

    Let's perform the multiplication:

        345
    x  789
    -------
     3105 (\(345 \times 9\))
    27600 (\(345 \times 80\))
    241500 (\(345 \times 700\))
    -------
    272205

    The result of the multiplication is \(272205\).

  3. Find the last three digits of the result:

    To find the last three digits of the product \(4321012345 \times 98766789\), we take the last three digits of \(272205\).

    \(272205 \pmod{1000} = 205\)

    The last three digits are \(2\), \(0\), and \(5\).

Conclusion

Therefore, the last three digits in the multiplication of \(4321012345 \times 98766789\) are \(2\), \(0\), and \(5\).

Was this answer helpful?

Similar Questions

  1. Let \(x\) and \(y\) be natural numbers, each less than 20, such that \(x\), \(y\), \(x+y\) and \(x-y\) are prime numbers. How many such combinations of \((x, y, x+y, x - y)\) are possible?
  2. A Question is given followed by two Statements I and II. Consider the Question and the Statements and mark the correct option.
    Question : Is \(r^n\) less than 1, where \(r\) is a real number and \(n\) is a natural number ?
    Statement-I : \(0 < r^2 < 1\)
    Statement-II : \(0 < r^3 < 2\)
    Which one of the following is correct in respect of the above Question and the Statements ?
  3. A Question is given followed by two Statements I and II. Consider the Question and the Statements and mark the correct option.
    Question : Is \((0.5)^n + (0.5)^{-n}\) always greater than 2, where \(n\) is an integer ?
    Statement-I : \(n\) is an even integer
    Statement-II : \(n\) is negative
    Which one of the following is correct in respect of the above Question and the Statements ?
  4. A Question is given followed by two Statements I and II. Consider the Question and the Statements and mark the correct option.
    Question : Let XYZ be a 3-digit number and the difference between XYZ and ZYX is equal to PQR. Is (P + R) equal to Q ?
    Statement-I : P = 3
    Statement-II : R = 6
    Which one of the following is correct in respect of the above Question and the Statements ?
  5. A Question is given followed by two Statements I and II. Consider the Question and the Statements and mark the correct option.
    Question : Is \((p^2 + q^2)\) always composite number, where \(p\) and \(q\) are different prime numbers ?
    Statement-I : \((p - q)\) is an odd integer
    Statement-II : \((p + q)\) is an odd integer
    Which one of the following is correct in respect of the above Question and the Statements ?
  6. The difference of the square of two natural numbers \(m\) and \(n\) (\(m > n\)) is 72. How many pairs of natural numbers will satisfy ?
  7. What is the sum of the largest and the smallest 4-digit numbers made by using single digit prime numbers (without repetition)?

  8. If \(11x + 5y\) is a prime number where \(x, y\) are natural numbers then what is the minimum value of \((x + y)\) ?

  9. A 4-digit number \(N\) has exactly 15 distinct divisors. What is the total number of distinct divisors of \(N^2\)?

  10. Consider the following statements in respect of \(p = n(n + 1)(n+2)(n + 3) + 1\), where \(n\) is a natural number :
    I. \(p\) is always odd
    II. \(p\) is a perfect square
    Which of the statements given above is/are correct?

Important Questions from Number System

  1. What is the value of 1 2 + 2 2 + 3 2 + ......21 2 ?

  2. Which sequence is correct to represent the hierarchical chain of number system?

    (Where N - Natural Numbers

    W - Whole Numbers

    Q - Rational Numbers

    Z - Integers)

  3. What must be added to 45680 to make it exactly divisible by 9?

  4. How many zeroes are there at the end of the following product? 

    1 x 5 x 10 x 15 x 20 x 25 x 30 x 35 x 40 x 45 x 50 x 55 x 60

  5. Let XYZ be a three-digit number, where (x + y + Z) is not a multiple of 3. Then (XYZ + YZX + ZXY) is not divisible by

Need Expert Advice?
Upcoming Exams
NDA
September 13, 2026
CDS
September 13, 2026
Test Series
CDS img
Defence
UPSC CDS 2026 Mock Test Series
540 Tests 4 Tests Free
1313 Attempts
4.3(170)
English, Hindi
More Questions from CDS

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