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What is strange number example?
Examples. The smallest weird number is 70. Its proper divisors are 1, 2, 5, 7, 10, 14, and 35; these sum to 74, but no subset of these sums to 70. The number 12, for example, is abundant but not weird, because the proper divisors of 12 are 1, 2, 3, 4, and 6, which sum to 16; but 2 + 4 + 6 = 12.
What is strange number in maths?
A “weird number” is a number that is abundant (i.e., the sum of proper divisors is greater than the number) without being pseudoperfect (i.e., no subset of the proper divisors sums to the number itself). The first few weird numbers are 70, 836, 4030, 5830, 7192, 7912, 9272, 10430.
Why is 70 a weird number?
Weird numbers are natural numbers that are abundant but not semiperfect. For example, 70 is the lowest weird number, because its set of proper divisors {1,2,5,7,10,14,35} sum to 74, but no subset of its set of proper divisors sum to the number 70, and 70 is the smallest number to meet such conditions.
How do you get a strange number?
We define “strange” numbers in the following way:
- All strange numbers are prime.
- Every single digit prime number is strange.
- A number with two or more digits is strange if, and only if, the two numbers obtained from it, by removing either its first or its last digit, are also strange.
Is 60 a weird number?
60 is a highly composite number. Because it is the sum of its unitary divisors (excluding itself), it is a unitary perfect number, and it is an abundant number with an abundance of 48. Being ten times a perfect number, it is a semiperfect number. It is the smallest number that is the sum of two odd primes in six ways.
What is strange number in Java?
The strange number is the square of the sum of its halves: 81 = (8 + 1)^2. Here are some other examples: 998001 = (998 + 001)^2, 3025 = (30 + 25)^2.
What is the most mysterious number?
6174
The number 6174 is a really mysterious number. At first glance, it might not seem so obvious….Two digits, five digits, six and beyond…
| Digits | Kernel |
|---|---|
| 2 | None |
| 3 | 495 |
| 4 | 6174 |
| 5 | None |
Why is 5 an untouchable number?
The number 5 is untouchable as it is not the sum of the proper divisors of any positive integer: 5 = 1 + 4 is the only way to write 5 as the sum of distinct positive integers including 1, but if 4 divides a number, 2 does also, so 1 + 4 cannot be the sum of all of any number’s proper divisors (since the list of factors …