100 has nine factors. 1, 2, 4, 5, 10, 20, 25, 50, 100
Three factors: 2, 4, 5 Three multiples: 200, 300, 400
No. The common factors of 12 and 100 are 1, 2, 4.
No numbers between 1 and 100 have exactly eleven factors. 60, 72, 84, 90 and 96 each have twelve factors.
Numbers having exactly three factors are the squares of prime numbers. Examples of these numbers greater than 100 are 121, 169, 289, 361, 529, 841, etc.
32 and 100 have three common factors. The second largest of these is 2.
20, 40, 60, 80
99 =3*3*11
Prime squares: 4, 9, 25 and 49.
6, 8 and 10 are three out of 32 possible answers.
878 three digit numbers have an even number of factors. Every factor of a number has a pair, so there ought to be an even number of factors for every number. However, if a pair of the factors are the same number, then there will be an odd number of factors, that is if the number is a perfect square. Assuming three digit numbers are 100 to 999: From 100 to 999, the perfect squares are 102 = 100 to 312 = 961, a total of 31-10+1 = 22 numbers. So of the 999-100+1 = 900 three digit numbers, 22 have an odd number of factors, so 900-22 = 878 have an even number of factors.
Three numbers.
30, 42, 66, 70 and 78.