120 hits per ball not counting putts, so a sleeve of Nike 2.5 dot Durability balls has 360 hits.
Assuming an average score of 65 with 25 putts per round for a total of 40 hits per round. So a sleeve lasts for 9, 18 hole rounds
There are some significant variables in earning XP. Playing tournaments pays more XP than just playing regular ranked rounds. Multi-player rounds earn a little more XP than playing tournament rounds. Of course your score also earns XP so the better you play the less XP per round you get. Awards also earn XP as does the days-in-a-row award
880 days-in-a-row XP + 65 score XP + 400 18 hole ranked round = 1345 XP
Add a second 18 hole round per day and the total XP per day would be 1800 XP per day and use up 2/3 of a ball. So you need to open a new sleeve every 4.5 days.
Level 96 to Level 99 requires accumulating 725112 XP.
So, 725112 XP / 1800 XP/day = 402.8 days
402.8 XP days / 4.5 days per sleeve = 90.8 sleeves
90.8 sleeves x 700 credits = 63,560 credits or 78.5 credits per round ($0.785)
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Level 96 XP 1291355
Level 97 XP 1513144
Level 98 XP 1764760
Level 99 XP 2016467
Level 100 XP 2268312