Q.17 select the correct numerical form of this number written in scientific notation. 1.2 × 10^4 0.00012 120,000 12,000 1,200

The answer is:  [D]:  "1,200" .

We take the "1.2" and move the decimal FOUR (4) places to the right.

So, when we move the decimal place ONE place to the right, we have "12". 
When we move it TWO places to the right, we have "120".
When we move it THREE places to the right, we have 1200".
When we move it FOUR places to the right, we have "1200".

Note:  When we move the "decimal place" to the right or left, and that "decimal place is "non-existent", we add a "zero to the [right or left].

"1200" can be written as:  "1,200" .

The answer is:  [D]:  " 1,200 " .