# Linear regression with linear scale as explanatory variable

I have a dataset containing values representing monthly sales in hypothetical e-commerce website. First columns contains order of particular month (eplanatory variable) and the second column (dependent variable) is value of sales in this month.

month_order value
1   2591
2   2262
3   2531
4   2379
5   2106
6   2500
7   2345
8   2200
9   2385
10  2991
11  2219
12  2600
13  3000


Equation of linear regression for this data set is:

f(x) = 27,42x + 2278


Question: Because I would like to make a very simple prediction of sales value in next month and I have no another more suitable eplanatory variable, may I use month_order and predict linear trend? In my case it would be:

f(14) = 27,42 * 15 + 2278 = 2689


is this correct in a theory of a linear regression and can I count it in this way?