Is 420 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 420 is composite or not first we have to find its factors.
Contents
Factors of 420:
- If we have taken numbers from 1, 2, 3…for checking factors of 420, we found that 420 has factors 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210 and 420. Hence, we must say that 420 is a composite number.
- Thus, 420 is the composite umber.
- If we multiply 420 by 1, 2, 3 then we get the multiples of 420 which are 420, 840 and so on.
About the number 420:
- 420 has more than two factors which are 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210 and 420 and hence it is the composite number.
- 420 is the even composite number and it is not the perfect square also.
- If we divide 420 by 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210 and 420 then we get remainder as zero. Hence, 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210 and 420 are the factors of 420.
Note:
- 420 is not the perfect square.
- Factors of 420: 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210 and 420
- Prime factors of 420: 2, 3, 5, 7
Conclusion:
- 420 is the composite number which has factors 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210
- And hence, 420 is not the prime number.
Multiple Choice Questions:
1) 420 is a
a) Prime number
b) Odd number
c) Composite number
d) Both b and c
Ans: c) composite number
2) The prime factors of a composite number 420 are
a) 2
b) 2, 3, 5, 7
c) 1, 4, 6, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210 and 420
d) 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 15, 20, 21, 28, 30, 35, 42, 60, 70, 84, 105, 140, 210 and 420
Ans: b) 2, 3, 5, 7
3) 420 is the even composite number because
a) It has two factors
b) More than two factors
c) Divisible by 2
d) Both b and c
Ans: d) both b and c