hello My question is that how can we express 315 in prime factor?
315 is first divisible by 5. I assume you know the divisibility rules.
61*5
Next, 61. Isn't that prime?
http://www.icteachers.co.uk/children/sats/primes.htm#1
To express 315 in prime factors, follow these steps:
Step 1: Start by dividing 315 by the smallest prime number, which is 2. However, 315 is not divisible by 2.
Step 2: Move on to the next prime number, which is 3. Divide 315 by 3, and you get 105.
Step 3: Now, divide 105 by the smallest prime number, which is 2. You get 52.5. Since 52.5 is not a whole number, we cannot divide it further by 2.
Step 4: Move on to the next prime number, which is 3. However, 52.5 is not divisible by 3.
Step 5: Now, divide 52.5 by the next prime number, which is 5. You get 10.5. Again, since 10.5 is not a whole number, we cannot divide it further by 5.
Step 6: Move on to the next prime number, which is 7. Divide 10.5 by 7, and you get 1.5. Since 1.5 is not a whole number, we cannot divide it further by 7.
Step 7: Finally, we have reached 1.5, which cannot be divided further by any prime numbers as it is not a whole number.
Step 8: Now, let's take note of the prime factors we used: 3, 3, 5, and 7.
Therefore, the prime factorization of 315 is 3 x 3 x 5 x 7, or you can write it as 3² x 5 x 7.