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Melhores sites skills 1-15:
1.
khanacademy.org 
414,640

2.
digiskills.pk 
133,840

3.
babbel.com 
131,890

4.
typeracer.com 
94,781

5.
igg.com 
76,203

6.
laopiniondemurcia.es 
31,198

7.
postcourier.com.pg 
27,300

8.
missoandfriends.com 
26,439

9.
activityvillage.co.uk 
24,422

10.
krazydad.com 
24,314

11.
sudoku.name 
24,042

12.
coolsite.co.il 
23,816

13.
youplay.com 
22,309

14.
mindgames.com 
22,230

15.
kakuroconquest.com 
16,715