How many significant figures are there in the measurement 238.230 kg?

Six .

The first things to look for here are non-zero digits, which as you know are always significant.

This measurement has a total of ##5## non-zero digits

##2,3,8,2,3##

so right from the start you know that it will have at least five significant figures.

Now focus on the trailing zero. Trailing zeros are zeros that follow a non-zero digit and are not followed by other non-zero digits.

When trailing zeros follow a non-zero digit and a decimal place, they are considered significant. This means that your measurement will contain ##6## significant figures

##238.230 ->## five non-zero digits and one significant trailing zero