To find all the divisors of the number 388,720:
- 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 388,720:
The prime factorization of a number: finding the prime numbers that multiply together to make that number.
388,720 = 24 × 5 × 43 × 113
388,720 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 = (4 + 1) × (1 + 1) × (1 + 1) × (1 + 1) = 5 × 2 × 2 × 2 = 40
But to actually calculate the factors, see below...
2. Multiply the prime factors of the number 388,720
- 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
composite factor = 2
2 =
4
prime factor =
5
composite factor = 2
3 =
8
composite factor = 2 × 5 =
10
composite factor = 2
4 =
16
composite factor = 2
2 × 5 =
20
composite factor = 2
3 × 5 =
40
prime factor =
43
composite factor = 2
4 × 5 =
80
composite factor = 2 × 43 =
86
prime factor =
113
composite factor = 2
2 × 43 =
172
composite factor = 5 × 43 =
215
composite factor = 2 × 113 =
226
composite factor = 2
3 × 43 =
344
composite factor = 2 × 5 × 43 =
430
composite factor = 2
2 × 113 =
452
composite factor = 5 × 113 =
565
This list continues below...
... This list continues from above
composite factor = 2
4 × 43 =
688
composite factor = 2
2 × 5 × 43 =
860
composite factor = 2
3 × 113 =
904
composite factor = 2 × 5 × 113 =
1,130
composite factor = 2
3 × 5 × 43 =
1,720
composite factor = 2
4 × 113 =
1,808
composite factor = 2
2 × 5 × 113 =
2,260
composite factor = 2
4 × 5 × 43 =
3,440
composite factor = 2
3 × 5 × 113 =
4,520
composite factor = 43 × 113 =
4,859
composite factor = 2
4 × 5 × 113 =
9,040
composite factor = 2 × 43 × 113 =
9,718
composite factor = 2
2 × 43 × 113 =
19,436
composite factor = 5 × 43 × 113 =
24,295
composite factor = 2
3 × 43 × 113 =
38,872
composite factor = 2 × 5 × 43 × 113 =
48,590
composite factor = 2
4 × 43 × 113 =
77,744
composite factor = 2
2 × 5 × 43 × 113 =
97,180
composite factor = 2
3 × 5 × 43 × 113 =
194,360
composite factor = 2
4 × 5 × 43 × 113 =
388,720
40 factors (divisors)
What times what is 388,720?
What number multiplied by what number equals 388,720?
All the combinations of any two natural numbers whose product equals 388,720.
1 × 388,720 = 388,720
2 × 194,360 = 388,720
4 × 97,180 = 388,720
5 × 77,744 = 388,720
8 × 48,590 = 388,720
10 × 38,872 = 388,720
16 × 24,295 = 388,720
20 × 19,436 = 388,720
40 × 9,718 = 388,720
43 × 9,040 = 388,720
80 × 4,859 = 388,720
86 × 4,520 = 388,720
113 × 3,440 = 388,720
172 × 2,260 = 388,720
215 × 1,808 = 388,720
226 × 1,720 = 388,720
344 × 1,130 = 388,720
430 × 904 = 388,720
452 × 860 = 388,720
565 × 688 = 388,720
20 unique multiplications The final answer:
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