10,20,30,40,50,60,70,80,90
Four numbers less than thirty, 12, 18, 20, and 28, each have exactly 6 factors.
Prime numbers
14 (I think).
there are 3 no.2,3 & 5
There are a few numbers that are less than 19 and have more than 4 factors. The number 10 is less than 19 and has more than four factors.
Four numbers less than thirty, 12, 18, 20, and 28, each have exactly 6 factors.
11
Prime numbers
Just 36.
14 (I think).
there are 3 no.2,3 & 5
They are: 2 3 5 and 7 all of which are prime numbers
Perfect squares have an odd number of factors. There are 31 perfect squares less than 1000.
They all are prime numbers except 1
There are a few numbers that are less than 19 and have more than 4 factors. The number 10 is less than 19 and has more than four factors.
All but the square numbers - 53 of them.
If the two numbers have no common factors other than 1, the LCM will be their product. If there are other common factors, the LCM will be less.