If your watch gains 2 minutes in every 24 hours, it means it gains 1 minute every 12 hours.
At 10 p.m. on Monday (12 hours later), your watch will show 10:02 p.m.
At 10 a.m. on Tuesday (24 hours later), your watch will show 10:02 a.m.
At 10 a.m. on Wednesday (48 hours later), your watch will show 10:04 a.m.
At 10 a.m. on the following Monday (7 days later), your watch will show 10:14 a.m. (since your watch gains 14 minutes in 7 days, which is 1 minute per 12 hours).