How to multiply some columns in matrix by scalar

I have a matrix with 12 columns. I want to multiply all columns except the first two by 100 and leave the first two the same, then output all this into a new matrix. How do i do this?

railwayarcsBIG = railwayarcs(:,2:12)*100;
% this code does not return the first two columns, it eliminates them and
% only does the scalar multiplication

Answer 1

[David Hill]

railwayarcsBIG=railwayarcs;
railwayarcsBIG(:,3:12)=railwayarcsBIG(:,3:12)*100;