Hello! Thank you for asking on HCM! You are right my lady, when you say digital BP measuring machines are sometimes incorrect ( they may lack appropriate calibration, or their battery may be almost expired and the machine doesn't properly work). I would not recommend digital machines, they are comfortable for solitary people, but they lack accuracy. Instead i advice a simple sphygmomanometer device. Only after using a correct measuring device, one can be sure in judging the presence of high BP.
Hope to have been helpful to you! Greetings! Dr. Iliri