May 20th
May 20th
Prime Numbers
A prime number is a number that is divisible by 1 and itself
only. Numbers that are notprime are called composite numbers. The
smallest prime number is 2. It is also the onlyeven prime number.
The prime numbers from 2 to 100 should be memorized. I
suggestmemorizing the primes in sets of 10. For example, learn
that 53 and 59 are the only primenumbers in the 50s.
List of Prime Numbers
| 2 |
3 |
5 |
7 |
| 11 |
13 |
17 |
19 |
| 23 |
29 |
|
|
| 31 |
37 |
|
|
| 41 |
43 |
47 |
|
| 53 |
59 |
|
|
| 61 |
67 |
|
|
| 71 |
73 |
79 |
|
| 83 |
89 |
|
|
| 97 |
|
|
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Questions involving prime numbers could ask for one specific
prime number greater thanor less than another number, or how many
primes are within a specific range.
Example:
What is the greatest prime number less than 25?
Knowing all the primes in the 20s (23, 29), the greatest prime
less than 25 is 23.
Example:
How many primes are between 10 and 20?
Knowing all the primes in the 10s (11, 13, 17, 19), there are
4 prime numbers from 10 to 20.
Learning primes is important because many other tricks come
from knowing prime numbers,including prime factorization, least
common multiple, greatest common divisor, andothers.
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