This concept has not shown up as often recently, but it is an important life skill. Also, other concepts build upon the principles learned from this one. It showed up just 2 times on high school tests this year, with a median placement at question # 21.
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Number Dojo Level: 82
The beauty of the metric system is that the measurements are converted using powers of 10--as opposed to multiples of 2 (volume), 3 or 12 or 16.5 or 1760 (distance), or multiples of 16 or 2000 (weight) in the English system of measurement.
The base units of the metric system are the liter (volume), meter (distance), and gram (mass--or weight for us non-scientists). There are many unit conversions to learn, but only 6 of them show up on number sense tests: They are distinguished by their prefixes:
hecto- (100 times the base unit)
deca- (10 times the base unit)
deci- (1/10 of the base unit)
centi- (1/100 of the base unit)
milli- (1/1000 of the base unit)
by: base unit
- Determine how many steps you need to move between the units.
- Multiply (if going from a larger measurement to a smaller one) or divide (if going from a smaller measurement to a larger one) by 10 to that power. This can be done most efficiently by moving the decimal that many steps to the right (if multiplying) or left (if dividing).
Example 1: 0.12 meters = ___ millimeters
- There are 3 steps between meters and millimeters, and we'll be multiplying.
- Move the decimal 3 steps to the right. The answer is 120.
Example 2: 0.065 Hectograms = ___ centigram(s)
- There are 2 steps down from Hecto- to the base unit, and another 2 from the base unit to centi-. We'll be multiplying.
- Move the decimal 4 steps to the right. The answer is 650.
Example 3: 600 centiliters = ___ decaliter(s)
- There are 2 steps up from centi- to the base unit, and another 1 step up to deca-. We'll be dividing.
- Move the decimal 3 steps to the left. The answer is .6
Example 4: 32.4 centimeters = ___ meters
- There are 2 steps up from centi- to the base unit. We'll be dividing.
- Move the decimal 2 steps to the left. The answer is .324
Example 5: 45.7 grams = ___ kilograms
- There are 3 steps up from the base unit to kilo-. We'll be dividing.
- Move the decimal 3 steps to the left. The answer is .0457