Hi Jouni,

The ranges are named for nice round numbers, but can actually measure values about 1.5x to 2x the indicated range (varies between channels).

Regarding the number of significant digits displayed: For resistance measurement there are adjustable internal amplifiers in the meter that have a certain amount of intrinsic noise. The amount of noise depends on the amplification level requested by the controller. The 1MΩ range involves an amplifier being turned all the way up, producing a higher noise level. The software knows what noise level to expect and truncates digits that will be too noisy to be useful.

I hope this answers your questions! Best
~James