Four out of nine, two out of nine, one out of nine, (), one out of 36, () find the law
Fill in the blanks: 4 / 9, 2 / 9, 1 / 9, (1 / 18), 1 / 36, (1 / 72)
Analysis: observe the given sequence of numbers and know that each number is the number in front of it multiplied by 1 / 2
1/9×1/2=1/18
1/36×1/2=1/72