Convert Whole Number to Hour, then Merge Hour with Date

I don't have my computer open so cannot verify this suggestion, so take it with a grain of salt:

In Power Query, try converting each column to text data type, then add a third that concatenation them with this bit of M code:

=Text.Combine( { [Date], " ", [Hour], ":00" } )

then convert that to DateTime.

It can probably be done in one long formula using Text.From( ) and DateTime.From( ) functions.

Hello

you can try this formula

DateTime.From( [Column A]) + #duration(0,[Column B],0,0)

here the complete code example that you can copy paste in the advanced editor to check how its working

let
	Source = #table
	(
		{"Column A","Column B"},
		{
			{"05/08/20","5"},	{"10/08/20","6"}
		}
	),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column A", type date}, {"Column B", Int64.Type}}),
    #"Added Custom" = Table.AddColumn(#"Changed Type", "Custom", each DateTime.From( [Column A]) + #duration(0,[Column B],0,0), type datetime )
in
    #"Added Custom"

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Kudoes are nice too

Have fun

Jimmy