Is 3920 is a composite number or not ?
- As we already know that, the number having factors 1 and the number itself is the prime number.
- And numbers having more than these two factors are the composite numbers.
- To check whether the number 3920 is composite or not first we have to find its factors.
Factors of 3920:
- If we have taken numbers from 1, 2, 3…for checking factors of 3920, we found that 3920 has factors 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920. Hence, we must say that 3920 is a composite number.
- Thus, 3920 is the composite number.
- If we multiply 3920 by 1, 2, 3 then we get the multiples of 3920 which are 3920, 7840 and so on.
About the number 3920:
- 3920 has more than two factors which are 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920 and hence it is the composite number.
- 3920 is the even composite number and it is not the perfect square also.
- If we divide 3920 by, 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920 then we get remainder as zero. Hence, 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920 are the factors of 3920.
Note:
- 3920 is not the perfect square.
- Factors of 3920: 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920
- Prime factors of 3920: 2, 5, 7
Conclusion:
- 3920 is the composite number which has factors, 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920
- And hence, 3920 is not the prime number.
Multiple Choice Questions:
1) 3920 is a
a) Prime number
b) Even number
c) Composite number
d) Both b and c
Ans: d) both b and c
2) The composite factors of a composite number 3920 are
a) 3920
b) 2, 5, 7
c) 4, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920
d) 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920
Ans: c) 4, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920
3) 3920 is composite number because
a) It has factors 1, 2, 4, 5, 7, 8, 10, 14, 16, 20, 28, 35, 40, 49, 56, 70, 80, 98, 112, 140, 196, 245, 280, 392, 490, 560, 784, 980, 1960 and 3920
b) It has more than two factors
c) Divisible by 2
d) Both a and b
Ans: d) both a and b