Final answer:
The number of different 10-letter words that can be formed from the given letters is 1,048,576.
Step-by-step explanation:
To find the number of different 10-letter words that can be formed from the given letters, we need to calculate the number of permutations. Since there are no restrictions on the repetition of letters, each of the 10 positions can be filled by any of the 4 letters. Therefore, the total number of different 10-letter words is 410 = 1,048,576.