When you are joining numbers together you may find that the number of decimal places dis-played is not as you require.
You can control the number of decimal places displayed using the Fixed function as shown below:
fixed([SampleInformation.DepthTop],1,false)
Fixed has 3 parameters, the field name to get the data from, the number of decimal places, and False (True would place a comma seperator value every 3 digits such as 1,000,000, where as false will display 1000000)