Abacus-based mental calculation (AMC), which was derived from the abacus, is the act of performing calculations, including addition, subtraction, multiplication, and division, in the mind by manipulating an imagined abacus.
ˈæbækəsbˈeɪst mˈɛntəl kˌælkjʊlˈeɪʃən ˌeɪˌɛmsˈiː, wˌɪtʃ wʌz dᵻɹˈaɪvd fɹʌmðɪ ˈæbækəs, ɪz ðɪ ˈækt ʌv pɚfˈɔːɹmɪŋ kˌælkjʊlˈeɪʃənz, ɪŋklˈuːdɪŋ ɐdˈɪʃən, sʌbtɹˈækʃən, mˌʌltɪplɪkˈeɪʃən, ænd dᵻvˈɪʒən, ɪnðə mˈaɪnd baɪ mənˈɪpjʊlˌeɪɾɪŋ ɐn ɪmˈædʒɪnd ˈæbækəs.