If you are not allowed to repeat the digits then the answer is clearly 0.If you are allowed to repeat digits then the only way you can possibly reach a product of 4 is by using a combination of 3 "1's" and 2 "2's". The possible combinations are therefore:22111212112112121112122111212112112112211121211122Thus there are 10 numbers which meet the criteria.
Yes.
When the two numbers are relatively prime.
19 and 2
8 and 2
All multiples are equal to the product of two numbers.
The product of the GCF and LCM of a pair of numbers is equal to the product of the numbers.
No, the product of two prime numbers is unique.
Expressed in digits, this is equal to 14,500,000.
I believe here are 51 such numbers.
If you are not allowed to repeat the digits then the answer is clearly 0.If you are allowed to repeat digits then the only way you can possibly reach a product of 4 is by using a combination of 3 "1's" and 2 "2's". The possible combinations are therefore:22111212112112121112122111212112112112211121211122Thus there are 10 numbers which meet the criteria.
factors
Two (or four) digits added together cannot equal 42. Two-digit numbers multiplied together cannot equal 82.
Yes.
3721
21.
none.