DEC_X_RANGE = (10..20) #第一个减数的范围 DEC_Y_RANGE = (1..20) #第二个减数的范围 LINE_CNTS = 5 #每行算式个数 DEC_FORMULA_CNTS = 100 #算式总的个数 res = {} while res.size < DEC_FORMULA_CNTS do x = rand(DEC_X_RANGE) y = rand(DEC_Y_RANGE) if (x-y) > 0 key = sprintf("%d-%d", x, y) str = sprintf("%-2d - %-2d = ", x, y) res[key] = str end end line = 0 res.each{|x,y| printf(y) line = line + 1 if line == LINE_CNTS puts "" puts "" line = 0 end }