SSC CHSL 7 Mar 2018 Shift 1 Paper

3 digit numbers that are divided by 4 are : 100,104,108,................,992,996
Above series is an A.P. with first term, $\mathit{a}=100,$ common difference , $\mathit{d}=4$ and last term , $\mathit{l}=996$
Thus, ${\mathit{n}}^{\mathit{t}\mathit{h}}$ term of an A.P., ${\mathit{A}}_{\mathit{n}}=\mathit{a}+\left(\mathit{n}-1\right)\mathit{d}$
⇒ $100+\left(\mathit{n}-1\right)4=996$
⇒ $\left(\mathit{n}-1\right)\times 4=996-100=896$
⇒ $\left(\mathit{n}-1\right)=\frac{896}{4}=224$
⇒ $\mathit{n}=224+1=225$
∴ There are 225 three digit numbers that are divided by 4.