Units of Measure

Prefixes

Strategy for conversions

  1. What unit is being asked for?
    • 500ml = ____L → liters
  2. What unit are you starting from?
    • 500ml = ____L → milliliters
  3. Which unit is larger? By how much is that unit larger?
    • Liters are the larger unit. Liters are 1,000X (103) greater than milliliters.
  4. Which direction are we moving?
    • Since we are moving to a larger unit, our value will be smaller. In this case, the value is smaller by 1,000X
    • In other words, the value is 1/1000 or 0.001 the value.
    • So what is the answer?

Factoring Out

Using the idea of factors of ten, you can assess the difference of the two units and cancel out the original unit algebraically to reach the desired final unit.

  • 500ml=_____L
    • 1ml=\frac{1}{1000}L or, \frac{1L}{1000ml}
      • which states 1000 milliliter in every 1 liter
    • 500ml\times\frac{1L}{1000ml}=\frac{500L}{1000}=0.5L
      • pay attention to the units and how we’ve canceled out the ml in the numerator of 500ml and in the denominator in the conversion of 1L in 1000ml
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