Convert a RGB colour value to Decimal

RGB integers are typically treated as three distinct bytes where the left-most (highest-order) byte is red, the middle byte is green and the right-most (lowest-order) byte is blue. You can retrieve the values of these individual bytes like this:

var c = 0xff03c0; // 16712640
var components = {
    r: (c & 0xff0000) >> 16, 
    g: (c & 0x00ff00) >> 8, 
    b: (c & 0x0000ff)
};

You can re-create a color from its components by shifting the bytes back in:

c = (components.r << 16) + (components.g << 8) + (components.b);

In your case, simply substitute components.r (etc) with your actual variables.

A much better answer (in terms of clarity) is this:

'Convert RGB to LONG:
 LONG = B * 65536 + G * 256 + R

'Convert LONG to RGB:
 B = LONG \ 65536
 G = (LONG - B * 65536) \ 256
 R = LONG - B * 65536 - G * 256

LONG is your long integer (decimal) that you want to make. Easy huh? Sure, bitshift