There cannot be a proper three digit number between 10 and 20. It must be a two digit number. If you consider a 2-digit number between 10 and 20, then its tens digit MUST be 1 and so MUST be odd.
So most of this question is either wrong or irrelevant. Are you sure you have not cut and pasted bits from two questions?
Meaningless question.
The largest three digit prime number whose digits are all primes is 773.
49 = 72 16 =4^
29
992
889
Meaningless question.
The largest three digit prime number whose digits are all primes is 773.
Nine hundred thirty (930) is the highest three digit number whose digits have a sum of 12. 9+3+0=12. Any numbers higher than that will give you an sum greater than 12.
What is the units digit of the least whole number greater than 1000 whose digits are all different?
49 = 72 16 =4^
29
961
992
940
97 is one example.
4