A non-touch thermometer to measure a temperature includes a microprocessor, a battery that is operably coupled to the microprocessor, a single button that is operably coupled to the microprocessor, a digital infrared sensor that is operably coupled to the microprocessor with no analog-to-digital converter operably coupled between the digital infrared sensor and the microprocessor, the digital infrared sensor having only digital readout ports, and a display device that is operably coupled to the microprocessor, wherein the microprocessor is operable to receive from the digital readout ports a digital signal that is representative of a temperature detected by the digital infrared sensor and the microprocessor is operable to determine a body core temperature from the digital signal that is representative of the temperature.