ORANGE is the mix of RED and GREEN and no BLUE. The amount of GREEN, and RED used is as follows, 100% for RED and 65% for GREEN. Full ORANGE then is at FFA500 at number 10 where RED is at its maximum of FF (255).

At number 11 we begin to show how the ORANGE color is lightened. We do this by changing the amount of GREEN and adding some BLUE. At number 12 the percentage of GREEN to RED used is at 73%, at 13 it is at 75%, at 15 it is 82%, at 17 it is 89% and at 19 it is 96% . The ratio between RED to GREEN also steadily increases. At number 20 it is 98% and the color turns to almost white.
At the same time the ratio by the addition of the BLUE steadily increases. At number 21 the blue is 10% of that of the RED. At each additional step the amount of the BLUE increases by 10% so by number 19 it is 90% of that of the of the RED.