Question 38695
I am needing a step-by-step process on how to convert kilometers to miles.
The problem is 4690 km to miles?
A FOOL PROOF UNIT CONVERSION METHOD IS GIVEN BELOW.
1.LIST OUT THE CONVERSION FACTORS.HERE,WE KNOW
A.1KM=1000 M
B.1M=100 CM
C.2.54 CM =1INCH
D.12 INCHES=1 FEET
E. 3 FT=1 YARD
F.1760 YARDS =1 MILE.
2.START WITH WHAT IS GIVEN.....4690 KM.
3.KEEP THE OBJECTIVE IN MIND.WE HAVE TO CONVERT THIS INTO MILES
4.NOW GO ON MULTIPLYING THE 4690 KM WITH UNIT RATIOS FROM ABOVE CONVERSION FACTORS,PUTTING THE UNITS EVERY TIME AND SEEING THAT AT THE END YOU GET ONLY MILES AND ALL REST OF THE UNITS GET CANCELLED.SEE THE WORKING BELOW.
5.UNIT RATIOS FROM ABOVE CONVERSIONS...
A.UNITY =1KM/1000M=1000 M/1 KM
B.UNITY = 1 M/100 CM = 100 CM/1 M.
C.UNITY = 2.54 CM/1 INCH = 1 INCH / 2.54 CM
D.UNITY = 12 INCHES/1 FT = 1 FT/12 INCHES
E.UNITY = 3 FT/1 YARD = 1 YARD /3 FT
F.UNITY = 1760 YARDS/1 MILE = 1 MILE/1760 YARDS.
6.WHICH UNITY RATIO YOU SHOULD USE BECOMES OBVIOUS WHEN YOU PUT THE UNITS.
SEE THE EXAMPLE
STARTING WITH 
4690 KM *1 KM/1000M...OR...WE SHOULD USE 4690 KM*1000M/1 KM IS THE QUESTION.THE GUIDING PRINCIPLE IS THAT WE SHOUD END UP WITH METERS ON CONVERSION WHICH HAPPENS IN THE SECOND CASE AS KM IN NUMERATOR CANCELS WITH KM IN DENOMINATOR LEAVING ONLY METRES.IN THE FIRST CASE WE GET KM*KM/METRE WHICH IS NOT WHAT WE WANT..SO FOLLOWING THIS PRINCIPLE WE GET
4690KM*(1000M/1KM)*(100CM/1M)*(1INCH/2.54CM)*(1FT/12INCHES)*(1YARD/3FT)*(1MILE/1760 YARDS)
NOTE THAT KM,M,CM.INCH,FEET,YARD ALL CANCEL OUT IN NUMERATOR AND DENOMINATOR LEVING ONLY MILES IN THE NUMERATOR WHICH IS WHAT WE WANT.IF WE MAKE A MISTAKE IN PUTTING THE UNIT RATIO APPROPRIATELY IT WILL IMMEDIATELY SHOW UP.
SO REST IS SIMPLE ARITHMATIC WHICH YOU CAN DO I SUPPOSE THE ANSWER IS
4690 KM = 2914.3 MILES