Playing with Nu...

Find the greatest common factor of $$42,126$$ and $$210$$.

Find the number of prime numbers between $$20$$ and $$40$$, both inclusive.

What is the sum of the least prime number and the greatest negative even integer?

What is the sum of the smallest prime and the largest prime less than $$10$$?

What is the greatest common factor of $$45,135$$ and $$270$$?

Each of the following is a factor of $$80$$, except

If the sum of the digits of a number is divisible by $$3$$, then the number is also divisible by __.

How many numbers are divisible by $$9$$?
$$863, 267, 129, 774, 981, 997, 936$$

Find the highest common factor of $$36$$ and $$84$$.

How many prime numbers are less than $$50$$?