How can I verify if a column is only decimal using Power Query M formula

Question

Power Query is new to me. Based on a search criterion for column 3, and assuming that those columns include only decimal values, I need to replace the value of column 4 with only decimal values in columns 5 and 6. The data file sample is as follows:

I tried to use Number.Mod , Value.Type and Value.Is functions but that did not work. Here is the code for my latest attempt:

    = Table.ReplaceValue(#"Changed Type",each [Column4],
  each if Text.Contains([Column3],"Instant Payment BSF/MBK") then 
          if Number.Mod([Column5], 1) = 0 then [Column5] 
          else if Number.Mod([Column6], 1) = 0 then [Column6]
          else [Column4]              
  else [Column4],Replacer.ReplaceValue,{"Column4"})

Answer 1

Try this:

= Table.ReplaceValue(#"Changed Type",each [Column4],
  each if Text.Contains([Column3],"Instant Payment") then 
          if Value.Is([Column4], type number) or Value.Is(Value.FromText([Column4]), type number) then [Column4]
          else if Value.Is([Column5], type number) or Value.Is(Value.FromText([Column5]), type number) then [Column5]
          else if Value.Is([Column6], type number) or Value.Is(Value.FromText([Column6]), type number) then [Column6]
          else [Column4]              
  else [Column4],Replacer.ReplaceValue,{"Column4"})