[tex] \frac{1}{10} < \frac{1}{90} + \frac{1}{91} + \frac{1}{92} + ... + \frac{1}{99} < \frac{1}{9} \\ \\ [/tex]
numitorul comun: 623171140431840
atunci=(623171140431840×9)/623171140431840
=> 66005056993773/623171140431840
=> 22001685664591/207723713477280
aproximativ 0,105918
1/10<0,105<1/9
0,10< 0,105<0.9
adevărat
