Here is a decomposition tree for 2045
#color(white)("XXxxxX")color(blue)(2025)#
#color(white)("XXxxxxX")darr#
#color(white)("XXxX")"-------------"#
#color(white)("XXx")darrcolor(white)("xxxxxx")darr#
#color(white)("XXX")color(red)5color(white)("xx")xxcolor(white)("xx")405#
#color(white)("XXxxxxxxxxX")darr#
#color(white)("XXxxxxxxX")"-----------"#
#color(white)("XXxxxxxX")darrcolor(white)("xxxx")darr#
#color(white)("XXxxxxxxX")color(red)5color(white)("x")xxcolor(white)("x")81#
#color(white)("XXxxxxxxxxxxxX")darr#
#color(white)("XXxxxxxxxxX")"--------------"#
#color(white)("XXxxxxxxxX")darrcolor(white)("xxxxxx")darr#
#color(white)("XXxxxxxxxxX")9color(white)("xx")xxcolor(white)("xx")9#
#color(white)("XXxxxxxxxX")darrcolor(white)("xxxxxx")darr#
#color(white)("XXXxxxxxx")"------"color(white)("xxx.x")"------"#
#color(white)("XXXxxxxx")darrcolor(white)("x")darrcolor(white)("xxx")darrcolor(white)("x")darr#
#color(white)("XXxxxxXX")color(red)3 xx color(red)3color(white)("xxxx"color(red)3 xxcolor(red)3#
So we have #2025= color(red)5^2xxcolor(red)3^2xxcolor(red)3^2#
#color(white)("XXX")=(color(red)5xxcolor(red)3xxcolor(red)3)^2#
#color(white)("XXX")=45^2#
Therefore
#color(white)("XXX")sqrt(2025)=sqrt((45^2))=45#