# How do you write 20,000 in scientific notation?

$2.0 \cdot {10}^{\cancel{5} 4}$
You would have to move the decimal place $\cancel{5}$4 units to the left so that it is after a significant figure (usually between the top two significant figures but as there is only one it is better to put it after). As the significant figure is greater than a whole number it will be to the power of positive $\cancel{5} 4$.
RW: Scientific notation requires a number to be written as a real number between 1 and 10 multiplied by the appropriate power of 10. Hence $20 , 000 = 2 \cdot {10}^{4}$