Find the number of distinct permutations of the word "CALCULATOR."​

L = -4 + (n - 1)(0.5), where n represents which term (1, 2, 3, ... ) and L represents the last term.

Step-by-step explanation:

We assume that this is an arithmetic sequence:  L = A + (n - 1)D, where L is the last figure, A is the first and D is the common difference.

Here we have -2.5 = -4 + (n - 1)D, where neither n nor D is specified.

If we arbitrarily let D = 0.5, then the terms of the sequence are

{-4, -3.5, -3, -2.5}, and n = 4:

Check:  If n = 4, what is the last term?  L = -4 + (4 - 1)(0.5), or

                                                                L = -4 + 3(0.5)  =  -4 + 1.5 = -2.5

Assuming an arithmetic sequence, the pattern is

L = -4 + (n - 1)(0.5)