Answer:
The least possible result is <em>-10</em>.
Step-by-step explanation:
Given the numbers 4, 5 and 6 are to be chosen one of the letters A, B or C.
First of all,
Let A = 4, B = 5 and C = 6

Let A = 4, B = 6 and C = 5

Let A = 5, B =4 and C = 6

Let A = 5, B = 6 and C = 4

Let A = 6, B = 4 and C = 5

Let A = 6, B = 5 and C = 4

Summarizing the above values in the form of a table:

So, the least possible result is <em>-10</em>.