Answer:
820
Step-by-step explanation:
If you use order of operations, you can find that 3x0 and 1x400x100x456x0 is just 0 so you just have to add 2x2 and 34x24. Which is 820
order of operations is
GEMDAS
Grouping symbols
exponents
multiplication and division (these don't have to be in order)
Addition and Subtraction (again, these don't have to be in order)
Base 10 has the ten digits: {0, 1, 2, 3, 4, 5, 6,7, 8, 9}
Base 11 has the digits: {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A} where A is treated as a single digit number
Base 12 has the digits {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B}
Base 13 has the digits: {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C}
Base 14 has the digits: {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D}
The digit D is the largest single digit of that last set. So the largest 3-digit base 14 integer is DDD which is the final answer
Note: It is similar to how 999 is the largest 3-digit base 10 integer