Mayur Arya
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How many three-digit prime numbers can you make using each of 2, 4, and 5 exactly once?

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You can form six numbers: 245, 254, 425, 452, 524, and 542. Among these, only 425 and 245 are primes. The others are divisible by 2 or 5, disqualifying them.

Class 6 NCERT Ganita Prakash Chapter 5 Prime Time

class 6 Mathematics Textbook Chapter 5 question answer

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  1. Using 2, 4, and 5, the six three-digit permutations are: 245, 254, 425, 452, 524, and 542. Checking their primality:
    • 245 is divisible by 5.
    • 254 is divisible by 2.
    • 425 is divisible by 5.
    • 452 is divisible by 2.
    • 524 is divisible by 2.
    • 542 is divisible by 2.
    Thus, none of these numbers are prime. Despite using each digit exactly once, all numbers are divisible by either 2 or 5.

    For more NCERT Solutions for Class 6 Math Chapter 5 Prime Time Extra Questions and Answer:
    https://www.tiwariacademy.com/ncert-solutions-class-6-maths-ganita-prakash-chapter-5/

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