Discussion
The smallest prime number greater than 48 is
*This question is included in Nova Math - Diagnostic: Test / Review, question #7
| (A) | 49 |
| (B) | ... |
| (C) | ... |
| (D) | ... |
| (E) | ... |
| (F) | ... |
The solution is
Posted: 01/30/2012 12:23
What is the best way to find out if a number is prime?
Posted: 01/31/2012 10:10
James, the usual way is to divide by other prime numbers, starting with the smallest such as 2, 3, 5, 7, 11, 13, etc.
If you can divide by 2, then it is not prime, e.g., 4.
If you can divide by 3, then it is not prime, e.g., 9
If you can divide by 5, then it is not prime, e.g., 10, 15, and all that ends in 0 and 5
and so on.
In the problem here, 49 is divisible by 7. 50 is divisible by 5. 51 is divisible by 3. 52 is divisible by 2. Hence we are left with the answer 53, E.
If you can divide by 2, then it is not prime, e.g., 4.
If you can divide by 3, then it is not prime, e.g., 9
If you can divide by 5, then it is not prime, e.g., 10, 15, and all that ends in 0 and 5
and so on.
In the problem here, 49 is divisible by 7. 50 is divisible by 5. 51 is divisible by 3. 52 is divisible by 2. Hence we are left with the answer 53, E.
Posted: 12/12/2012 12:42
Try to count with me, starting from 48:
48,49,50,51,52,53. Hey, we just got the answer! It is however (E).
48,49,50,51,52,53. Hey, we just got the answer! It is however (E).