5/12 vs 11/21
5/12 * 21/21 vs 11/21 * 12/12
60 / 252 vs 132/252
The right side is bigger.
- Or -
Look at 5/12. Half of 12 is 6, so 5/12 is smaller than a half.
Look at 11/21. Half of 11/21 is 10.5, so 11/21 is bigger than a half.
5/12 is smaller than 11/21.
Answer: No, 5/12 is not greater than 11/21.