50
The largest 4-digit number with two different digits is 9998. Its successor is the next number, which is 9999. However, 9999 has only one digit (9), so we need to find the next valid 4-digit number with two different digits. This number is 10000, which is technically a 5-digit number, so the largest valid number with two different digits before 9999 is 9998, and its successor cannot be a 4-digit number with two different digits. Thus, there is no valid successor that meets the criteria.
100000 2847239582
2178
You had me until "product." The product of 4 digits can't be prime.
27
The last digit is always the estimated digit in a number
There are about 10-11 digits in a number
45
Find a four digit number whose digits will be reversed when multiplied by nine?
34.
-8
100000 2847239582
The units digit of a two digit number exceeds twice the tens digit by 1. Find the number if the sum of its digits is 10.
47 Impossible problem!
2178
Find the greatest product of five consecutive digits in the 1000-digit number.7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450
You had me until "product." The product of 4 digits can't be prime.