Easy way of conversion of units

Note: Decametre is sometimes symbolically represented as Dm but that’s an unofficial notation.

A mnemonic in English to learn these units:
King Harry Died Mother Didn’t Cry Much

You can learn it in Hindi as:
Kal Hum Dost Mile Dilli City Mein

There are two more mnemonics for learning the units of Litre and Gram:
Kal Hum Dost Lade Dilli City Mein
Kal Hum Dost Gaye Dilli City Mein

So these are 7 units. The middle unit is Metre which is the 4th unit, so assign Metre a value of 1 and from Metre increase the number of zeros one by one for each unit to the top of the table and to the bottom of the table.

Remember, when you are converting from Larger unit to Smaller unit, you will have to “Multiply” and when you are converting from Smaller unit to Larger unit, you will have to “Divide”.

Following are some examples of conversions.

• Conversion from decimetre to millimetre

            1dm = 1 $\times $ 100 mm = 100mm

            35dm = 35 $\times $ 100 mm = 3500mm

Here, we will first see the difference of zeros between these two units; Decimetre(10) has one zero and Millimetre(1000) has three zeros, so the difference of zeros between them is of two zeros. Since, we are converting from larger unit to smaller unit, we will multiply with 100 (having two zeros).

• Conversion from hectometre to kilometre

            1hm = $\frac{1}{10}$ km = 0.1km

            45hm = $\frac{45}{10}$ km = 4.5km

Here in the above conversion also, we will see the difference of zeros between these two units; Hectometre(100) has two zeros and Kilometre(1000) has three zeros, so the difference of zeros between them is of one zero. Since, we are converting from smaller unit to larger unit, we will divide by 10 (having one zero).
In the same way, we can easily do conversion of any other units also.

Note: The conversions of litres and grams are done in the same above way.

Conversion of squares and cubes of units

• Conversion from ${{m}^{2}}$ to $c{{m}^{2}}$

           $1{{m}^{2}}=1m\times 1m=100cm\times 100cm=10000c{{m}^{2}}$

           $3.2{{m}^{2}}=3.2\times 100cm\times 100cm=32000c{{m}^{2}}$

• Conversion from $c{{m}^{3}}$ to ${{m}^{3}}$

           $1c{{m}^{3}}=1cm\times 1cm\times 1cm=\frac{1}{100}m\times \frac{1}{100}m\times \frac{1}  {100}m$
                 
                    $= \frac{1}{1000000}{{m}^{3}}=0.000001{{m}^{3}}$

           $230000c{{m}^{3}}=230000\times \frac{1}{100}m\times \frac{1}{100}m\times \frac{1}{100}m=\frac{230000}{1000000}{{m}^{3}}=0.23{{m}^{3}}$


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