Problem: convert #3.44xx10^8# inches to miles.
First determine the relationships between inches and feet, and feet and miles.
#"12 in"="1 ft"#
#"5280 ft=1 mi"#
Multiply #3.44xx10^8# inches by #(1 "ft")/(12"in")# to get ft.
#3.44xx10^8cancel"in"xx(1 "ft")/(12 cancel"in")=2.867xx7 "ft"#
Multiply #2.867xx10^7"ft"xx(1"mi")/(5280 "ft")# to get mi.
#2.867xx10^7cancel"ft"xx(1 "mi")/(5280 cancel"ft")=5.43xx10^3 "mi"# (rounded to three significant figures.
You can carry out both conversions together.
#3.44xx10^8cancel"in"xx(1cancel"ft")/(12cancel"in")xx(1"mi")/(5280cancel"ft")=5.43xx10^3"mi"# (rounded to three significant figures)