Number.Sqrt Function of Power Query
 The Number.Sqrt function in Power Query returns the square root of a number. If number is null, Number.Sqrt returns null. 
Syntax
 Number.Sqrt(number as nullable number) as nullable number 
Example: Add a column with the square root of values.
Power Query M
let
    // Step 1: Create sample data
    Source = Table.FromRecords({
        [ID = 1, Value = 4],
        [ID = 2, Value = 9],
        [ID = 3, Value = -16],
        [ID = 4, Value = 25],
        [ID = 4, Value = 60]
    }),
    // Step 2: Add a new column with square root of 'Value'
    AddSquareRoot = Table.AddColumn(Source, "SquareRoot", each Number.Sqrt([Value]), type number)
in
    AddSquareRoot         The output of the above code is shown below:
