A digital thermometer reads 15 degrees Celsius, what is the uncertainty?

The uncertainty of the accurate measurement of temperature with a digital thermometer ranges from - 1 to + 1. So, here in this case, the uncertainty in temperature will be 14 degree to 16 degree Celsius.

Explanation:

The Uncertainty in Measurement

The measurements of objects we observe through our eyes using analog or digital equipment, have some uncertainties. it's not surely the accurate measurement that we observe. Hence, while taking measurements, we must have taken an uncertainty range in the values.

For example, if we take a digital thermometer, which measures the temperature as 15 degree Celsius; it means that the accurate temperature may vary from by the difference of either - 1 or + 1 i. e., either 14 degree Celsius or 16 degree Celsius. The same way, the uncertainty range is - 0.5 to + 0.5 when we use analog thermometer.