7*11, 7*13 -> 2 numbers. There are no other subcases. So, 2 + 14 + 9 + 5 + 2 = 32. There are 32 numbers from 1 to 100 with 4 factors.
Which of these numbers has exactly 4 factors?
Any prime number raised to the third power has exactly four factors: 1, prime, prime², prime³ For example: 3³ = 27. Factors of 27: 1, 3, 9, 27.
Is 4 a factor of the following numbers?
All the multiples of 4 have 4 as a factor. The multiples of 4 are 4, 8, 12, 16, 20, and so on.
How many numbers from 1 to 100 have exactly 3 factors?
The factors must be prime, since any non-prime factor would itself have factors, meaning we’d exclude for example 2 x 3 x 4 = 24 since 4 is 2 x 2, so 24 really has 4 factors. Prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23 – anything over this cannot result in a combined result of 100 or less (since 2 x 2 x n = 100 gives n = 25).
Are there any numbers that have exactly 4 factors?
The square of a prime p has 3 factors: 1, p, and p^2. But the cube of p has 4 factors also: 1, p, p^2, and p^3. So my answer is the product of 2 distinct primes, and the cube of a prime. I’m pretty sure there aren’t any others. 25 insanely cool gadgets selling out quickly in 2021.
What are two numbers less than 50 that have exactly 3 factors?
You should have probably mentioned “2 digit numbers less than 50 that have exactly 3 factors”, because this is the property of a square number of a prime and there are 4 squares below 50 that are the squares of prime numbers. There are 4 numbers as shown below and two of them are 2 digit numbers and the remaining 2 numbers are single digit numbers.
Are there any prime numbers with exactly 3 factors?
So, there are no prime numbers with exactly three factors. Why are there 25 prime numbers from 1-100? Each of the 25 prime numbers from 1 to 100 has exactly two factors, 1 and the number itself. The other 75 numbers from 1 to 100 are not prime numbers because none of them have exactly two factors.
