11
11
9
What number best completes the sequence 1 1/2 5 10 1/2 18
13 20 12
The letter is L and the number is 12.
The sequence appears to alternate between adding and subtracting numbers. The pattern seems to be +11, -7, +5, -2, +6. Following this pattern, the next number in the sequence would be +3 from the previous number, which would be 21.
Not sure about completes becasue the series look like it should be infinite. The best continuation is 28, 32, ...
15.
15, since 15*2 = 9*2 + 12*2
2 6 3 8 6 12 2 6 3 8 6 12
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1