The solution to the problem is as follows:
1∙5µm² = ? m²
1m * 1m = 1m²
But 1m = 1,000,000µm = 1x10^6µm
1x10^6µm * 1x10^6µm = 1m²
1x10^12µm² = 1m² (Now, divide both sides by 1x10^12).
1x10^12µm² /(1x10^12) = 1m² /(1x10^12)
1µm² = 0∙000 000 000 001 m² (x both sides by by 1∙5).
1∙5µm² = 0∙000 000 000 0015 m²
1∙5µm² = 1∙5x10^-12 m²
I hope my answers has come to your help. God bless and have a nice day ahead!