QUESTION

CSAT

Easy

Maths

Prelims 2024

How many consecutive zeros are there at the end of the integer obtained in the product 12×24×36×48×....×25501^2 \times 2^4 \times 3^6 \times 4^8 \times.... \times 25^{50}?

Select an option to attempt

Explanation

To find the number of trailing zeros in the product 12×24×36××255012 \times 24 \times 36 \times \dots \times 2550, we need to count the number of times 10 appears in this product. Since each 10 is created by a pair of 2 and 5, and there are always more factors of 2, the number of zeros at the end of the product depends on the number of factors of 5. Steps:

  1. Identify terms that contribute factors of 5: We look at multiples of 5 in the sequence and count their factors of 5:
  • 5105^{10} contributes 10 factors of 5
  • 102010^{20} contributes 20 factors of 5
  • 153015^{30} contributes 30 factors of 5
  • 204020^{40} contributes 40 factors of 5
  • 255025^{50} contributes 100 factors of 5
  1. Add up the factors of 5: 10+20+30+40+100=20010 + 20 + 30 + 40 + 100 = 200

So, the product has 200 trailing zeros\textbf{200 trailing zeros}.

Trusted by 2L aspirants

Practice UPSC Prelims PYQs Smarter

Practice Now
  • Track accuracy & weak areas
  • See past trends & repeated themes
Start Practicing Now

Crack UPSC with your
Personal AI Mentor

An AI-powered ecosystem to learn, practice, and evaluate with discipline

SuperKalam is your personal mentor for UPSC preparation, guiding you at every step of the exam journey.

Download the App

Get it on Google PlayDownload on the App Store
Follow us

ⓒ Snapstack Technologies Private Limited