1+ 1=2 (numerator of the second digit), 2+ 1=3 (denominator of the second digit).
2+3=5 (numerator of the third number) and 3+5=8 (denominator of the third number).
5+8= 13 (numerator of the fourth digit), 8+ 13=2 1 (denominator of the fourth digit).
13+2 1=34 (numerator of the fifth digit), 2 1+34=55 (denominator of the fifth digit).
So the next number should be 34/55.
The second question first looks at the law. 1, 2, 4, 7, 1 1, 16, 22, 29, ... as follows
The topic "1, 2, 3, 4, 5, 6, 7, ..." gives eight numbers. Calculate the ninth number, which should be (1+2+3+4+5+6+7+8)+1= 37.
The number of nine has eight differences (1+2+3+4+5+6+7+8), and finally 1 is added because the first number is 1, which can be regarded as a cardinal number.
Know the number 1997 in the same way: there is a difference of 1996 between the first number and the last number, that is
1,2,3,4,5,...... 1995, 1996。 Now it becomes the formula (1+2+3+4+5+...1995+1996)+1.
Is the combination algorithm, such as 1996+4, 1995+5, ... 100 1+999, one * * has 996 2000s, plus 1000 and.
1,2,3. Get 1993006, and finally add the cardinality 1, 1997, and the number is 1993007.