GregOr 41 35.4.6 : ܟܕ ܓܝܪ ܡܬܬܠܬ ܫܒܘܥܐ܃ ܠܗܢܐ ܡܢܝܢܐ ܥܒܕ‏ : for when seven is multiplied by three, it makes this number (i.e., 21)
See the entire entry for šāḇōˁ, šāḇōˁā n.m. week

GregOr 41 35.4.6 :ܟܕ ܓܝܪ ܡܬܬܠܬ ܫܒܘܥܐ܃ ܠܗܢܐ ܡܢܝܢܐ ܥܒܕ‏ : for when seven is multiplied by three, it makes this number (i.e., 21)
See the entire entry for tlt vb. D to do three times