really depends what game type he is playing, while i find deathmatch and domination the most fun, it takes forever to rank up even finishing almost every challenge. i sat on the first 55 for over a week (probably about 1 day worth of play at least) and i just hit 12 days about to go into the 10th prestige within the next couple of days. if he is playing search and destroy, sabotage, or headquarters, he could have put in less than 10 days and got up to the 10th prestige. remember, 1 kill in s&d = 5 kills in deathmatch, 10 kills in domination. defusing the bomb = 10 kills in deathmatch, 20 kills in domination for just defusing 1 time. s&d can rack up points extremely quick, especially on a good team that knows how to max out the points each round. not quite sure on the point spread for sabotage, but planting/defusing usually gets a lot of points, same with holding down the headquarters.