To find all the divisors of the number 78,400:
- 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 78,400:
The prime factorization of a number: finding the prime numbers that multiply together to make that number.
78,400 = 26 × 52 × 72
78,400 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 = (6 + 1) × (2 + 1) × (2 + 1) = 7 × 3 × 3 = 63
But to actually calculate the factors, see below...
2. Multiply the prime factors of the number 78,400
- 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
prime factor =
7
composite factor = 2
3 =
8
composite factor = 2 × 5 =
10
composite factor = 2 × 7 =
14
composite factor = 2
4 =
16
composite factor = 2
2 × 5 =
20
composite factor = 5
2 =
25
composite factor = 2
2 × 7 =
28
composite factor = 2
5 =
32
composite factor = 5 × 7 =
35
composite factor = 2
3 × 5 =
40
composite factor = 7
2 =
49
composite factor = 2 × 5
2 =
50
composite factor = 2
3 × 7 =
56
composite factor = 2
6 =
64
composite factor = 2 × 5 × 7 =
70
composite factor = 2
4 × 5 =
80
composite factor = 2 × 7
2 =
98
composite factor = 2
2 × 5
2 =
100
composite factor = 2
4 × 7 =
112
composite factor = 2
2 × 5 × 7 =
140
composite factor = 2
5 × 5 =
160
composite factor = 5
2 × 7 =
175
composite factor = 2
2 × 7
2 =
196
composite factor = 2
3 × 5
2 =
200
composite factor = 2
5 × 7 =
224
composite factor = 5 × 7
2 =
245
This list continues below...
... This list continues from above
composite factor = 2
3 × 5 × 7 =
280
composite factor = 2
6 × 5 =
320
composite factor = 2 × 5
2 × 7 =
350
composite factor = 2
3 × 7
2 =
392
composite factor = 2
4 × 5
2 =
400
composite factor = 2
6 × 7 =
448
composite factor = 2 × 5 × 7
2 =
490
composite factor = 2
4 × 5 × 7 =
560
composite factor = 2
2 × 5
2 × 7 =
700
composite factor = 2
4 × 7
2 =
784
composite factor = 2
5 × 5
2 =
800
composite factor = 2
2 × 5 × 7
2 =
980
composite factor = 2
5 × 5 × 7 =
1,120
composite factor = 5
2 × 7
2 =
1,225
composite factor = 2
3 × 5
2 × 7 =
1,400
composite factor = 2
5 × 7
2 =
1,568
composite factor = 2
6 × 5
2 =
1,600
composite factor = 2
3 × 5 × 7
2 =
1,960
composite factor = 2
6 × 5 × 7 =
2,240
composite factor = 2 × 5
2 × 7
2 =
2,450
composite factor = 2
4 × 5
2 × 7 =
2,800
composite factor = 2
6 × 7
2 =
3,136
composite factor = 2
4 × 5 × 7
2 =
3,920
composite factor = 2
2 × 5
2 × 7
2 =
4,900
composite factor = 2
5 × 5
2 × 7 =
5,600
composite factor = 2
5 × 5 × 7
2 =
7,840
composite factor = 2
3 × 5
2 × 7
2 =
9,800
composite factor = 2
6 × 5
2 × 7 =
11,200
composite factor = 2
6 × 5 × 7
2 =
15,680
composite factor = 2
4 × 5
2 × 7
2 =
19,600
composite factor = 2
5 × 5
2 × 7
2 =
39,200
composite factor = 2
6 × 5
2 × 7
2 =
78,400
63 factors (divisors)
What times what is 78,400?
What number multiplied by what number equals 78,400?
All the combinations of any two natural numbers whose product equals 78,400.
1 × 78,400 = 78,400
2 × 39,200 = 78,400
4 × 19,600 = 78,400
5 × 15,680 = 78,400
7 × 11,200 = 78,400
8 × 9,800 = 78,400
10 × 7,840 = 78,400
14 × 5,600 = 78,400
16 × 4,900 = 78,400
20 × 3,920 = 78,400
25 × 3,136 = 78,400
28 × 2,800 = 78,400
32 × 2,450 = 78,400
35 × 2,240 = 78,400
40 × 1,960 = 78,400
49 × 1,600 = 78,400
50 × 1,568 = 78,400
56 × 1,400 = 78,400
64 × 1,225 = 78,400
70 × 1,120 = 78,400
80 × 980 = 78,400
98 × 800 = 78,400
100 × 784 = 78,400
112 × 700 = 78,400
140 × 560 = 78,400
160 × 490 = 78,400
175 × 448 = 78,400
196 × 400 = 78,400
200 × 392 = 78,400
224 × 350 = 78,400
245 × 320 = 78,400
280 × 280 = 78,400
32 unique multiplications The final answer:
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