Numbers that are prime can't be multiples of 10.
Multiples of 10 can't be odd.
10, 20, 30 and so on.
The composite odd numbers from 9 to 99.
There are 10 numbers less than 101 which have an odd number of factors: 1,4,9,16,25,36,49,64,81,100.
No odd number less than hundred has 12 factors other numbers which has 12 factors are 60, 72, 84, 90 and 96. But they all are even numbers. The answer will be different if you consider negative numbers, however.
11,22,33,44,55,66,77,88,99
4, 9, 25 and 49 They are squares of prime numbers.
If the GCF of a given pair of numbers is 1, the LCM will be equal to their product. If the GCF is greater than 1, the LCM will be less than their product. Or, stated another way, if the two numbers have no common prime factors, their LCM will be their product.
All even numbers greater than 2 have even proper factors, since they all have 2 as a proper factor.
The numbers for which the sum of its proper factors is 1 less than the number is the powers of 2; less than 50 these are: 2, 4, 8, 16 & 32.
Square numbers, like 36 and 64.
There are four odd numbers less that 100 that have 6 factor. This does not compare with even numbers that have 12 factors!
60, 72, 84, 90 and 96 each have twelve factors.
0, 1, 2, 3
The most factors any odd number less than 100 has is 6. There are 4 numbers which have 6 factors:45, 63, 75 & 99.
There are 10 numbers less than 101 which have an odd number of factors: 1,4,9,16,25,36,49,64,81,100.
44 and 45 75 and 76 98 and 99
The proper factors of a number are all its factors except itself. Sometimes, the number 1 is also excluded. So, the proper factors of 6 are either 1, 2, and 3, or if excluding the number 1, they are 2 and 3. (If your instructor distinguishes between proper factors and proper divisors, then proper factors are all the factors of a number except 1 and itself, while proper divisors are all the factors of a number except itself, but often proper factors is the only term used, so check whether 1 is included in the definition you are using.)The list of factors in the question "What are the factors of the numbers from 1 to 100" (see link below) includes both 1 and the number itself, but if you remove the number itself, and the 1 if it is excluded in the definition of proper factor that you are using, you will have the complete list of proper factors.The prime numbers, which only have themselves and 1 as factors, are in bold in the list of factors on that page. Their proper factors are either the number 1, or if 1 is excluded, they have no proper factors.Short List of Proper Factors:As an example, here are the proper factors (including 1, which is sometimes used and sometimes not) for the first 10 numbers:1: No proper factors2: 13: 14: 1, 25: 16: 1, 2, 37: 18: 1, 2, 49: 1, 310: 1, 2, 5A less unwieldy versionIn practice, it seems unlikely that anyone wants you to continue the above list to 100. (That would be 3 sides of handwritten A4 paper.) Maybe they only wanted to know which numbers appear in the list of proper factors. For example, the proper factors of numbers from 1 to 10 are 1, 2, 3, 4 and 5 (as you can see above).
By some definitions prime numbers don't have proper factors. In other definitions, their only proper factor is 1. Either way, your answer is the next prime number after 50, which would be 53.
Prime numbers