$\text{a)}230=2,3\cdot {10}^2$

$\text{b)}3600=3,6\cdot {10}^3$

$\text{c)}18000=1,8\cdot {10}^4$

$\text{d)}195000=1,95\cdot {10}^5$

$\text{e)}120000=1,2\cdot {10}^5$

$\text{f)}13400000=1,34\cdot {10}^7$