AboutAbe Mantell Expertise Hello, I am a college professor of mathematics and regularly teach all levels from elementary mathematics through differential equations, and would be happy to assist anyone with such questions!
Experience Over 15 years teaching at the college level.
Expert: Abe Mantell Date: 7/11/2008 Subject: how do i covert in the metric system
Question I'm having a test monday and I'm having trouble converting.
Answer Hello Julia,
The easiest way to do any conversions is to use what are called
"unit fractions." That is, you multiply by "1" but use appropriate
units -- of course you must know some conversions!!!
Here are some examples:
1. Convert 8 inches to cm...since there are 2.54 cm to an inch,
-- we multiply 8 in. by (2.54 cm / 1 in.), cm's in the numerator
-- and inches in the denominator so after multiplying the inches
-- "divide" out and "cm" remain. Thus we get 8*2.54=20.32 cm
2. Convert 10 km to miles...if we know how many km's there are in a
-- mile, then that will be the quickest! There are about 1.609 km
-- per mile. So, we want to multiply 10 km by (1 mile / 1.609 km)
-- so that the "km" divide out and we are left with "miles"...
-- thus, we get 10/1.609 miles or about 6.22 miles.
-- If we did not know that conversion between km and miles, then we'd
-- need to use other units to get the same result...it would just
-- take longer. For example, we know there are 1000 meters per km,
-- so 10 km = 10*1000 meters = 10,000 m. We know there are 2.54 cm
-- to an inch, so there are (2.54 cm / 1 inch)*(12 inches / 1 ft)
-- which is 30.48 cm to a ft...we also know there are 5280 ft to
-- a mile. So...there are (30.48 cm / 1 ft)*(5280 ft / 1 mile)
-- so there are 160934.4 cm per mile. But there are 100 cm per meter
-- so there are (160934.4 cm / 1 mile)*(1 meter / 100 cm), which
-- gives 1609.344 meter per mile. Now we can convert our 10 km or
-- 10,000 meter to miles!
-- (10,000 m / 1)*(1 mile / 1609.344 m) or about 6.21 miles.
