Question

David takes 300 milligrams of medicine every day. How many grams is this?

Answer 1

Hint: We know the standard relation between grams and milligrams as $1{\text{ gm}} = 1000{\text{ mgs}}$. Use this formula and apply a unitary method to find the number of grams in 300 milligrams.

Complete step-by-step solution:
According to the question, 300 milligrams of medicine is taken by David every day. We have to find how many grams this is.
We know that grams and milligrams are related by the formula as shown below:
$ \Rightarrow 1{\text{ gm}} = 1000{\text{ mgs}}$
In this formula, if we transfer 1000 on the other side to find the number of grams present in one milligrams then we can easily apply a unitary method to determine the same thing for 300 milligrams. So we have:
$
   \Rightarrow 1{\text{ mg}} = \dfrac{1}{{1000}}{\text{ gms}} \\
   \Rightarrow 1{\text{ mg}} = 0.001{\text{ gms}}
 $
Now, as discussed earlier, we can apply a unitary method to calculate the same thing of 300 milligrams.
If a unit milligram is equivalent to 0.001 grams then 300 milligrams will be equivalent to the product of 300 with 0.001:
$
   \Rightarrow 300{\text{ mg}} = 300 \times 0.001{\text{ gms}} \\
   \Rightarrow 300{\text{ mg}} = 0.3{\text{ gms}}
 $

Thus, David takes 0.3 grams of medicine every day.

Additional Information: Some other important relations between different units of mass are given below:
$
   \Rightarrow 1{\text{ kg}} = 1000{\text{ gms}} \\
   \Rightarrow 1{\text{ Quintal}} = 100{\text{ kgs}} \\
   \Rightarrow 1{\text{ ton}} = 10{\text{ Quintals}}
 $

Note: Using unitary methods, we solve the problem by first finding the value of one unit and then finding the required value by multiplying the single unit value with necessary value. This method is widely used in time and distance problems and in time and work problems.