Theory:

Natural number
Reciprocal
 Decimal expansion
 Nature of decimal expansion 
\(2\)\(1/2\)12=0.5Terminating decimal expansion
\(3\)\(1/3\)13=0.33333...=0.3¯Non-terminating and recurring decimal expansion
\(4\)\(1/4\)14=0.25Terminating decimal expansion
\(5\)\(1/5\)15=0.2Terminating decimal expansion
\(6\)\(1/6\)16=0.16666...=0.16¯Non-terminating and recurring decimal expansion
\(7\)\(1/7\)17=0.142857142857...=0.142857¯Non-terminating and recurring decimal expansion
\(8\)\(1/8\)18=0.125Terminating decimal expansion
\(9\)\(1/9\)19=0.11111...=0.1¯Non-terminating and recurring decimal expansion
\(10\)\(1/10\)110=0.1Terminating decimal expansion
\(11\)\(1/11\)111=0.090909...=0.09¯Non-terminating and recurring decimal expansion
\(12\)\(1/12\)112=0.083333...=0.083¯Non-terminating and recurring decimal expansion
\(13\)\(1/13\)113=0.076923076923...=0.076923¯Non-terminating and recurring decimal expansion
\(14\)\(1/14\)114=0.0714285714285...=0714285¯Non-terminating and recurring decimal expansion
\(15\)\(1/15\)115=0.06666...=06¯Non-terminating and recurring decimal expansion
\(16\)\(1/16\)116=0.0625Terminating decimal expansion
\(17\)\(1/17\)117=0.588235294117647...=0.0588235294117647¯Non-terminating and recurring decimal expansion
\(18\)\(1/18\)118=0.0555555...=05¯Non-terminating and recurring decimal expansion
\(19\)\(1/19\)119=0.052631578947368421...=0.052631578947368421¯Non-terminating and recurring decimal expansion
\(20\)\(1/20\)120=0.05Terminating decimal expansion
\(21\)\(1/21\)121=0.047619¯Non-terminating and recurring decimal expansion
\(22\)\(1/22\)122=045¯Non-terminating and recurring decimal expansion
\(23\)\(1/23\)123=0.0434782608695652173913...=0434782608695652173913¯Non-terminating and recurring decimal expansion
\(24\)\(1/24\)124=0.041666...=0.0416¯Non-terminating and recurring decimal expansion
\(25\)\(1/25\)125=0.04Terminating decimal expansion