More Advanced Metrics
Metrics gets a little trickier when you have to convert from the English (Standard) system to the Metric (SI) system. If you know the basic principle, it's not bad though.
To convert between the two, you need to know some equivalents. For example, 1 inch is approximately 2.54 centimeters and 1 kilometer is about .62 miles. These can be set up as a fraction:1"/2.54cm. Because these are equivalent, that's a fraction equivalent to 1/1. You can multiply or divide numbers by this ratio and it works out great. Let me demonstrate.
5 kilometers = ? miles.
Don't know? Well, if we set this up as a fraction, we can write it as 5k/1, because if we divide anything by 1 it's just the same. Now, we put in the equivalent fraction (1k = .62 miles). We want the kilometers to cancel out, so we put them opposite. We are then left with:
| 5 k | | .62 mi | | ? |
| ----- | X | ----- | = |
| 1 | | 1 k | |
The kilometers cancel out and we are left with 5 X .62 miles, or 3.1 miles. That wasn't too hard, was it?
Let's try something a little more tricky.
45,900,000 cm. equates to how many miles?
Well, you can either change it to inches and then convert it to miles, or you can change it to kilometers and then convert over. Which is easier? Let's look.
| 45,900,000 cm | | 1 in | | 1 ft | | 1 mile | | ? |
| ---------------- | X | --------- | X | ------- | X | -------- | = |
| 1 | | 2.54 cm | | 12 in | | 5280 ft | |
Ug. That looks painful. Let's change centimeters to kilometers first. Remember, you only have to move the decimal, and in this case, it's 5 places to the left. That gets rid of all those zeroes. You then have 459 km, and it's only one step to convert that to miles.
| 459 k | | .62 mi | | ? |
| ------- | X | ------- | = |
| 1 | | 1 k | |
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