When alphabets are assigned numerical values:

GHI = 789 DEF = 456 ABC = 123 According to the question: GHI = 1578 Calculation: $789 \times 2 = 1578$

DEF = 912 Calculation: $456 \times 2 = 912$

ABC = 246 Calculation: $123 \times 2 = 246$

Thus, the pattern involves doubling the given numerical value for each set of alphabets.