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Question
State if the following is a prime number?
397
Solution
A number between 100 and 200 is a prime number if it is not divisible by any prime number less than 15.
Similarly, a number between 200 and 300 is a prime number if it is not divisible by any prime number less than 20.
397 is a prime number because it is not divisible by 2, 3, 5, 7, 11, 13, 17, and 19.
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|
Number |
Divisible by |
||||||||
|
2 |
3 |
4 |
5 |
6 |
8 |
9 |
10 |
11 |
|
|
128 |
Yes |
No |
Yes |
No |
No |
Yes |
No |
No |
No |
|
990 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
1586 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
275 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
6686 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
639210 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
429714 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
2856 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
3060 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
|
406839 |
______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ | ______ |
