To find all the divisors of the number 40,320:
- 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 40,320:
The prime factorization of a number: finding the prime numbers that multiply together to make that number.
40,320 = 27 × 32 × 5 × 7
40,320 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 = (7 + 1) × (2 + 1) × (1 + 1) × (1 + 1) = 8 × 3 × 2 × 2 = 96
But to actually calculate the factors, see below...
2. Multiply the prime factors of the number 40,320
- 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 = 2
3 =
8
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
4 =
16
composite factor = 2 × 3
2 =
18
composite factor = 2
2 × 5 =
20
composite factor = 3 × 7 =
21
composite factor = 2
3 × 3 =
24
composite factor = 2
2 × 7 =
28
composite factor = 2 × 3 × 5 =
30
composite factor = 2
5 =
32
composite factor = 5 × 7 =
35
composite factor = 2
2 × 3
2 =
36
composite factor = 2
3 × 5 =
40
composite factor = 2 × 3 × 7 =
42
composite factor = 3
2 × 5 =
45
composite factor = 2
4 × 3 =
48
composite factor = 2
3 × 7 =
56
composite factor = 2
2 × 3 × 5 =
60
composite factor = 3
2 × 7 =
63
composite factor = 2
6 =
64
composite factor = 2 × 5 × 7 =
70
composite factor = 2
3 × 3
2 =
72
composite factor = 2
4 × 5 =
80
composite factor = 2
2 × 3 × 7 =
84
composite factor = 2 × 3
2 × 5 =
90
composite factor = 2
5 × 3 =
96
composite factor = 3 × 5 × 7 =
105
composite factor = 2
4 × 7 =
112
composite factor = 2
3 × 3 × 5 =
120
composite factor = 2 × 3
2 × 7 =
126
composite factor = 2
7 =
128
composite factor = 2
2 × 5 × 7 =
140
composite factor = 2
4 × 3
2 =
144
composite factor = 2
5 × 5 =
160
composite factor = 2
3 × 3 × 7 =
168
composite factor = 2
2 × 3
2 × 5 =
180
composite factor = 2
6 × 3 =
192
This list continues below...
... This list continues from above
composite factor = 2 × 3 × 5 × 7 =
210
composite factor = 2
5 × 7 =
224
composite factor = 2
4 × 3 × 5 =
240
composite factor = 2
2 × 3
2 × 7 =
252
composite factor = 2
3 × 5 × 7 =
280
composite factor = 2
5 × 3
2 =
288
composite factor = 3
2 × 5 × 7 =
315
composite factor = 2
6 × 5 =
320
composite factor = 2
4 × 3 × 7 =
336
composite factor = 2
3 × 3
2 × 5 =
360
composite factor = 2
7 × 3 =
384
composite factor = 2
2 × 3 × 5 × 7 =
420
composite factor = 2
6 × 7 =
448
composite factor = 2
5 × 3 × 5 =
480
composite factor = 2
3 × 3
2 × 7 =
504
composite factor = 2
4 × 5 × 7 =
560
composite factor = 2
6 × 3
2 =
576
composite factor = 2 × 3
2 × 5 × 7 =
630
composite factor = 2
7 × 5 =
640
composite factor = 2
5 × 3 × 7 =
672
composite factor = 2
4 × 3
2 × 5 =
720
composite factor = 2
3 × 3 × 5 × 7 =
840
composite factor = 2
7 × 7 =
896
composite factor = 2
6 × 3 × 5 =
960
composite factor = 2
4 × 3
2 × 7 =
1,008
composite factor = 2
5 × 5 × 7 =
1,120
composite factor = 2
7 × 3
2 =
1,152
composite factor = 2
2 × 3
2 × 5 × 7 =
1,260
composite factor = 2
6 × 3 × 7 =
1,344
composite factor = 2
5 × 3
2 × 5 =
1,440
composite factor = 2
4 × 3 × 5 × 7 =
1,680
composite factor = 2
7 × 3 × 5 =
1,920
composite factor = 2
5 × 3
2 × 7 =
2,016
composite factor = 2
6 × 5 × 7 =
2,240
composite factor = 2
3 × 3
2 × 5 × 7 =
2,520
composite factor = 2
7 × 3 × 7 =
2,688
composite factor = 2
6 × 3
2 × 5 =
2,880
composite factor = 2
5 × 3 × 5 × 7 =
3,360
composite factor = 2
6 × 3
2 × 7 =
4,032
composite factor = 2
7 × 5 × 7 =
4,480
composite factor = 2
4 × 3
2 × 5 × 7 =
5,040
composite factor = 2
7 × 3
2 × 5 =
5,760
composite factor = 2
6 × 3 × 5 × 7 =
6,720
composite factor = 2
7 × 3
2 × 7 =
8,064
composite factor = 2
5 × 3
2 × 5 × 7 =
10,080
composite factor = 2
7 × 3 × 5 × 7 =
13,440
composite factor = 2
6 × 3
2 × 5 × 7 =
20,160
composite factor = 2
7 × 3
2 × 5 × 7 =
40,320
96 factors (divisors)
What times what is 40,320?
What number multiplied by what number equals 40,320?
All the combinations of any two natural numbers whose product equals 40,320.
1 × 40,320 = 40,320
2 × 20,160 = 40,320
3 × 13,440 = 40,320
4 × 10,080 = 40,320
5 × 8,064 = 40,320
6 × 6,720 = 40,320
7 × 5,760 = 40,320
8 × 5,040 = 40,320
9 × 4,480 = 40,320
10 × 4,032 = 40,320
12 × 3,360 = 40,320
14 × 2,880 = 40,320
15 × 2,688 = 40,320
16 × 2,520 = 40,320
18 × 2,240 = 40,320
20 × 2,016 = 40,320
21 × 1,920 = 40,320
24 × 1,680 = 40,320
28 × 1,440 = 40,320
30 × 1,344 = 40,320
32 × 1,260 = 40,320
35 × 1,152 = 40,320
36 × 1,120 = 40,320
40 × 1,008 = 40,320
42 × 960 = 40,320
45 × 896 = 40,320
48 × 840 = 40,320
56 × 720 = 40,320
60 × 672 = 40,320
63 × 640 = 40,320
64 × 630 = 40,320
70 × 576 = 40,320
72 × 560 = 40,320
80 × 504 = 40,320
84 × 480 = 40,320
90 × 448 = 40,320
96 × 420 = 40,320
105 × 384 = 40,320
112 × 360 = 40,320
120 × 336 = 40,320
126 × 320 = 40,320
128 × 315 = 40,320
140 × 288 = 40,320
144 × 280 = 40,320
160 × 252 = 40,320
168 × 240 = 40,320
180 × 224 = 40,320
192 × 210 = 40,320
48 unique multiplications The final answer:
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