[tex]\it 2021\cdot2^{2022}\cdot5^{2021}=2021\cdot2\cdot2^{2021}\cdot5^{2021}=4042\cdot(2\cdot5)^{2021}=4042\cdot10^{2021}=\\ \\ =4042\cdot1\underbrace{000\ ...\ 0}_{2021\ zerouri}=4042\underbrace{000\ ...\ 0}_{2021\ zerouri}[/tex]
Suma cifrelor este egală cu 4+4+2= 10