To find all the divisors of the number 18,900:
- 1. Decompose the number into prime factors.
- See how you can find out how many factors (divisors) the number has, without actually calculating them.
- 2. Multiply the prime factors in all their unique combinations, that yield different results.
1. Carry out the prime factorization of the number 18,900:
The prime factorization of a number: finding the prime numbers that multiply together to make that number.
18,900 = 22 × 33 × 52 × 7
18,900 is not a prime number but a composite one.
- Prime number: a natural number that is divisible (divided evenly) only by 1 and itself. A prime number has exactly two factors: 1 and the number itself.
- Examples of prime numbers: 2 (factors 1, 2), 3 (factors 1, 3), 5 (factors 1, 5), 7 (factors 1, 7), 11 (factors 1, 11), 13 (factors 1, 13), ...
- Composite number: a natural number that has at least one factor other than 1 and itself. So it is neither a prime number nor 1.
- Examples of composite numbers: 4 (it has 3 factors: 1, 2, 4), 6 (it has 4 factors: 1, 2, 3, 6), 8 (it has 4 factors: 1, 2, 4, 8), 9 (it has 3 factors: 1, 3, 9), 10 (it has 4 factors: 1, 2, 5, 10), 12 (it has 6 factors: 1, 2, 3, 4, 6, 12), ...
How to count the number of factors of a number?
Without actually finding the factors
- If a number N is prime factorized as:
N = am × bk × cz
where a, b, c are the prime factors and m, k, z are their exponents, natural numbers, .... - ...
- Then the number of factors of the number N can be calculated as:
n = (m + 1) × (k + 1) × (z + 1) - ...
- In our case, the number of factors is calculated as:
- n = (2 + 1) × (3 + 1) × (2 + 1) × (1 + 1) = 3 × 4 × 3 × 2 = 72
But to actually calculate the factors, see below...
2. Multiply the prime factors of the number 18,900
- Multiply the prime factors involved in the prime factorization of the number in all their unique combinations, that give different results.
- Also consider the exponents of these prime factors.
- Also add 1 to the list of factors (divisors). All the numbers are divisible by 1.
All the factors (divisors) are listed below - in ascending order
The list of factors (divisors):
Numbers other than 1 that are not prime factors are composite factors (divisors).
neither prime nor composite =
1
prime factor =
2
prime factor =
3
composite factor = 2
2 =
4
prime factor =
5
composite factor = 2 × 3 =
6
prime factor =
7
composite factor = 3
2 =
9
composite factor = 2 × 5 =
10
composite factor = 2
2 × 3 =
12
composite factor = 2 × 7 =
14
composite factor = 3 × 5 =
15
composite factor = 2 × 3
2 =
18
composite factor = 2
2 × 5 =
20
composite factor = 3 × 7 =
21
composite factor = 5
2 =
25
composite factor = 3
3 =
27
composite factor = 2
2 × 7 =
28
composite factor = 2 × 3 × 5 =
30
composite factor = 5 × 7 =
35
composite factor = 2
2 × 3
2 =
36
composite factor = 2 × 3 × 7 =
42
composite factor = 3
2 × 5 =
45
composite factor = 2 × 5
2 =
50
composite factor = 2 × 3
3 =
54
composite factor = 2
2 × 3 × 5 =
60
composite factor = 3
2 × 7 =
63
composite factor = 2 × 5 × 7 =
70
composite factor = 3 × 5
2 =
75
composite factor = 2
2 × 3 × 7 =
84
composite factor = 2 × 3
2 × 5 =
90
composite factor = 2
2 × 5
2 =
100
composite factor = 3 × 5 × 7 =
105
composite factor = 2
2 × 3
3 =
108
composite factor = 2 × 3
2 × 7 =
126
composite factor = 3
3 × 5 =
135
This list continues below...
... This list continues from above
composite factor = 2
2 × 5 × 7 =
140
composite factor = 2 × 3 × 5
2 =
150
composite factor = 5
2 × 7 =
175
composite factor = 2
2 × 3
2 × 5 =
180
composite factor = 3
3 × 7 =
189
composite factor = 2 × 3 × 5 × 7 =
210
composite factor = 3
2 × 5
2 =
225
composite factor = 2
2 × 3
2 × 7 =
252
composite factor = 2 × 3
3 × 5 =
270
composite factor = 2
2 × 3 × 5
2 =
300
composite factor = 3
2 × 5 × 7 =
315
composite factor = 2 × 5
2 × 7 =
350
composite factor = 2 × 3
3 × 7 =
378
composite factor = 2
2 × 3 × 5 × 7 =
420
composite factor = 2 × 3
2 × 5
2 =
450
composite factor = 3 × 5
2 × 7 =
525
composite factor = 2
2 × 3
3 × 5 =
540
composite factor = 2 × 3
2 × 5 × 7 =
630
composite factor = 3
3 × 5
2 =
675
composite factor = 2
2 × 5
2 × 7 =
700
composite factor = 2
2 × 3
3 × 7 =
756
composite factor = 2
2 × 3
2 × 5
2 =
900
composite factor = 3
3 × 5 × 7 =
945
composite factor = 2 × 3 × 5
2 × 7 =
1,050
composite factor = 2
2 × 3
2 × 5 × 7 =
1,260
composite factor = 2 × 3
3 × 5
2 =
1,350
composite factor = 3
2 × 5
2 × 7 =
1,575
composite factor = 2 × 3
3 × 5 × 7 =
1,890
composite factor = 2
2 × 3 × 5
2 × 7 =
2,100
composite factor = 2
2 × 3
3 × 5
2 =
2,700
composite factor = 2 × 3
2 × 5
2 × 7 =
3,150
composite factor = 2
2 × 3
3 × 5 × 7 =
3,780
composite factor = 3
3 × 5
2 × 7 =
4,725
composite factor = 2
2 × 3
2 × 5
2 × 7 =
6,300
composite factor = 2 × 3
3 × 5
2 × 7 =
9,450
composite factor = 2
2 × 3
3 × 5
2 × 7 =
18,900
72 factors (divisors)
What times what is 18,900?
What number multiplied by what number equals 18,900?
All the combinations of any two natural numbers whose product equals 18,900.
1 × 18,900 = 18,900
2 × 9,450 = 18,900
3 × 6,300 = 18,900
4 × 4,725 = 18,900
5 × 3,780 = 18,900
6 × 3,150 = 18,900
7 × 2,700 = 18,900
9 × 2,100 = 18,900
10 × 1,890 = 18,900
12 × 1,575 = 18,900
14 × 1,350 = 18,900
15 × 1,260 = 18,900
18 × 1,050 = 18,900
20 × 945 = 18,900
21 × 900 = 18,900
25 × 756 = 18,900
27 × 700 = 18,900
28 × 675 = 18,900
30 × 630 = 18,900
35 × 540 = 18,900
36 × 525 = 18,900
42 × 450 = 18,900
45 × 420 = 18,900
50 × 378 = 18,900
54 × 350 = 18,900
60 × 315 = 18,900
63 × 300 = 18,900
70 × 270 = 18,900
75 × 252 = 18,900
84 × 225 = 18,900
90 × 210 = 18,900
100 × 189 = 18,900
105 × 180 = 18,900
108 × 175 = 18,900
126 × 150 = 18,900
135 × 140 = 18,900
36 unique multiplications The final answer:
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