a=1/100+1/101+1/102+....1/299
de la 100 la 299 sunt 299-100+1=200 de numere
1/299+1/299+1/299+....1/299<1/100+1/101+1/102+..1/299<1/100+1/100+1/100+….+1/100; (200 de termeni)
200/299 < 1/100+1/101+1/102+....1/299 <200/100
200/299 < a < 2
a ∈(200/299; 2); deci, a∈(200/299; 2]