$a\times {10}^{\text{n}}$

$1\le a<10$

$\text{n = integers}$

Example 1

$\text{a.}598000000=5.98\times {10}^8$

$\text{b.}0.0000652=6.52\times {10}^{-5}$

Example 2

$\text{a.}30000\text{ m}+24000\text{ m}$

$3.0\times {10}^4\text{ m}+2.4\times {10}^4\text{ m}$

$5.4\times {10}^4\text{ m}$

$\text{b.}0.00856\text{ mm}-0.00078\text{ mm}$

$8.56\times {10}^{-3}\text{ mm}-7.8\times {10}^{-4}\text{ mm}$

$8.56\times {10}^{-3}\text{ mm}-0.78\times {10}^{-3}\text{ mm}$

$7.78\times {10}^{-3}\text{ mm}$

PREFIXES

$$\begin{array}{ccccc}\text{Prefix}& & \text{Symbol}& & \text{Factor of 10}\\ \\ \text{peta}& & \text{P}& & {10}^{15}\\ \\ \text{tera}& & \text{T}& & {10}^{12}\\ \\ \text{giga}& & \text{G}& & {10}^9\\ \\ \text{mega}& & \text{M}& & {10}^6\\ \\ \text{kilo}& & \text{k}& & {10}^3\\ \\ \text{hecto}& & \text{h}& & {10}^2\\ \\ \text{deca}& & \text{da}& & {10}^1\\ \\ \text{deci}& & \text{d}& & {10}^{-1}\\ \\ \text{centi}& & \text{c}& & {10}^{-2}\\ \\ \text{milli}& & \text{m}& & {10}^{-3}\\ \\ \text{micro}& & \mu & & {10}^{-6}\\ \\ \text{nano}& & \text{n}& & {10}^{-9}\\ \\ \text{pico}& & \text{p}& & {10}^{-12}\end{array}$$

Example:

$2.5\text{ nm}=\dots \text{ km}$

$\text{nano}={10}^{-9}$

$\text{kilo}={10}^3$

Then subtract the power of 10 of nano to the power of 10 of kilo

$2.5\text{ nm}=2.5\times {10}^{-9-3}\text{ km}=2.5\times {10}^{-12}\text{ km}$

CONVERSION