Three digits can't possibly add up to 900.
The largest possible sum of 3 digits is (9 + 9 + 9) = 27.
Find a four digit number whose digits will be reversed when multiplied by nine?
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?
There are 21.
22
The largest three digit prime number whose digits are all primes is 773.
137?
992
940
How about: 773
The largest 3 digit number whose digits are all primes is 777. The largest 3 digit number with different prime digits is 753.
1348.
450 or 900
Find a four digit number whose digits will be reversed when multiplied by nine?
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.
1
There is no number. 100 is the only one that has a hundreds digit. It's impossible.