Transform to negative numbers

If you expenses are in their own column, just choose Standard | Multiply from the Number Column area of the Transform ribbon and enter -1. Here is the M code:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMtY31zcyMDRX0lEyNVCK1QGJWMBEDA2AQrEA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [Date = _t, Value = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Date", type date}, {"Value", Int64.Type}}),
    #"Multiplied Column" = Table.TransformColumns(#"Changed Type", {{"Value", each _ * -1, type number}})
in
    #"Multiplied Column"

efilipe

You can add a conditional column and then delete the original one.

let
    Source = Excel.Workbook(File.Contents("C:\ Transform to negative numbers.xlsx"), null, true),
    Table1_Table = Source{[Item="Table1",Kind="Table"]}[Data],
    #"Changed Type" = Table.TransformColumnTypes(Table1_Table,{{"data", type date}, {"tipo", type text}, {"destino", type text}, {"meio", type text}, {"conta", type text}, {"valor", Int64.Type}}),
    #"Added Conditional Column" = Table.AddColumn(#"Changed Type", "valor_updated", each if [tipo] = "Saída" then -[valor] else [valor] ),
    #"Changed Type1" = Table.TransformColumnTypes(#"Added Conditional Column",{{"valor_updated", Int64.Type}}),
    #"Removed Columns" = Table.RemoveColumns(#"Changed Type1",{"valor"}),
    #"Renamed Columns" = Table.RenameColumns(#"Removed Columns",{{"valor_updated", "valor"}})
in
    #"Renamed Columns"

Best Regards,

Herbert