Write an expression for the quantity 506 000 cm in which it is clear that all zeros are significant

The use of scientifice notation ensures you that all the zeros shown are significative.

For exampleif you wrire 4.30 * 10^ 5 means that there are 3 significant figures because the 0 counts, and if you wirte 4.300 * 10^5 means that there are 4 significant figures becasue the two zeros count.

So, if you want to state the  number of significant figures in 506000 cm, write it in scientific notation with all the zeros: 5.06000 * 10^5 cm