TY JOUR TI FEATURES OF CALCULATION AND ANALYSIS OF THE INDICATOR «ADDED VALUE» IN SMALL BUSINESS KW small business KW simplified taxation system KW value added KW calculation KW analysis KW economic and mathematical model JO Bulletin of the Angarsk State Technical University AU Bychkova, G.M. AU Kulakova, I.M. PY 2023 IS 1 PB Federal State Funded Educational Establishment of Higher Education «Angarsk State Technical University»