Is 645 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 645 is composite or not first we have to find its factors.
Contents
Factors of 645:
- If we have taken numbers from 1, 2, 3…for checking factors of 645, we found that 645 has factors 1, 3, 5, 15, 43, 129, 215 and 645. Hence, we must say that 645 is a composite number.
- Thus, 645 is the composite number.
- If we multiply 645 by 1, 2, 3 then we get the multiples of 645 which are 645, 1290 and so on.
645 is a Composite number or Prime number
About the number 645:
- 645 has more than two factors which are 1, 3, 5, 15, 43, 129, 215 and 645 and hence it is the composite number.
- 645 is the odd composite number and it is not the perfect square also.
- If we divide 645 by 1, 3, 5, 15, 43, 129, 215 and 645 then we get remainder as zero. Hence, 1, 3, 5, 15, 43, 129, 215 and 645 are the factors of 645.
Note:
- 645 is not the perfect square.
- Factors of 645: 1, 3, 5, 15, 43, 129, 215 and 645
- Prime factors of 645: 3, 5, 43
Conclusion:
- 645 is the composite number which has factors 1, 3, 5, 15, 43, 129, 215 and 645.
- And hence, 645 is not the prime number.
Multiple Choice Questions:
1) 645 is a
a) odd number
b) Prime number
c) Composite number
d) Both a and c
Ans: d) both a and c
2) The prime factors of a composite number 645 are
a) 1
b) 3, 5, 43
c) 1, 15, 129, 215 and 645
d) 1, 3, 5, 15, 43, 129, 215 and 645
Ans: b) 3, 5, 43
3) 645 is the odd composite number because
a) It has factors 1, 3, 5, 15, 43, 129, 215 and 645
b) It is divisible by 2
c) It is not divisible by 2
d) Both a and c
Ans: d) both a and c