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im trying to create macro that will SUM cells
at the right end cell of columns in G column it should SUM numbers from D:F (green numbers)
at the bottom cells in row 6 it should SUM numbers from 3:5
bottom right cell should SUM green numbers

in this example it's like this

G3.Value = "=SUM(D3:F3)"
G4.Value = "=SUM(D4:F4)"
G5.Value = "=SUM(D5:F5)"

D6.Value = "=SUM(D3:D5)"
E6.Value = "=SUM(E3:E5)"
F6.Value = "=SUM(F3:F5)"

G6.Value = "=SUM(G3:G5)"

this table will grow so macro would be very very helpfull
there is no option to do it manually ... no time for that
i'm trying to avoide human erorr

i have the idea that i should set variables for first&last used row and first&last used column and then to sum only numbers
but my knowleage stops there

one thing that is very important for me is that cell needs to have =SUM function ... i can't use Application.Sum(Range) because sometimes it will happen that i need to change some numbers and i need live SUM update