Carson has four blocks that are numbered 4, 1, 7, and 8. What is the greatest number that Carson can create using the blocks?

The given digits are 4, 1, 7, and 8.

The largest number that can be created 

= (largest digit × 1000) + (second largest digit × 100) + (third largest digit × 10) + fourth largest digit

= (8 × 1000) + (7 × 100) + (4 × 10) + 1 

= 8000 + 700 + 40 + 1 

= 8741

Hence, 8741 is the greatest number that can be obtained using given digits.