It is based on powers of 10, making it logical.
Answer:
.125
Step-by-step explanation:
4 is one-eighth (1/8) of 32, which would be represented by the decimal .125 or 0.125
Here is a list of the odd number paired
1+3, 1+5, !+7, and !+9 (there are 4 unique sums - 4, 6,8 and 10)
3+5, 3+7, 3+9 (notice I did not pair 3 with 1 and the the only new sum is 12)
5+7, 5+9 (the only new sum is 14)
7+9 (16 is a new sum)
The sums (no repeats) are 4,6,8,10,12,14 and 16 for a total of seven numbers.