Length
5
10
20
30
40
50
100
Open
Level
1
2
3
4
5
6
7
8
9
10
15
20
50
Timer
None
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0:30
1:00
2:00
3:00
4:00
5:00
10:00
20:00
30:00
Feedback
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On
1
2
3
4
Animate
No
Yes
Prime numbers
Prime factors
Greatest common factor
Least common multiple
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See correct answer
Factors
17
Prime
OK
Composite
Right
Wrong
Clock
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Math
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