last update value

[Sam.K]

Hi, my excel workseet have 12 column of column a,b,c,d,e,f,g,h,i,j,k,l. but when i input the value to each column ,only the last value will show up in the cell p3 how can i do..eg,
if the last cell input in column g1=615 the cell p3 will be=615
if the last cell input in column k1=850 the cell p3 will be=850
if the last cell input in column L1 =890 the cell p3 will be=890
Please see the attach file ,thank