Suppose that, from measurements in a microscope, you determine that a certain layer of graphene covers an area of 1.50μm2. convert this to square meters.
express the area in square meters to three significant figures.

For the answer to the question above,
1∙5µm² = ? m² 
1m * 1m = 1m²     But 1m = 1,000,000µm = 1x 10^6µm   1x10^6µm * 1x10^6µm = 1m²      1x 10^12µm² = 1m² (Now, try dividing both sides by 1x10^12).   1x10^12µm² /(1x10^12) = 1m² /(1x10^12)    1µm² = 0∙000 000 000 001 m² (multiply both sides by by 1∙5).    1∙5µm² = 0∙000 000 000 0015 m²   

 1∙5µm² = 1∙5x 10^-12 m²
I hope this helps