Question

The longest telescope in D.O.S.A is 14.70 metres long. If the telescope has a sensor at every 70 centimetres, the total number of sensors in it is

• A. 2
• B. 12
• C. 21
• D. 22

Answer 1

The correct option is C 21

The length of the telescope is $14.7metres$.

To convert from metres to centimetres, follow the process:


So, $1m$ $=100cm$.

$\therefore 14.7m$ $=14.7\times 100=1470cm$.

Now, the telescope has a sensor at every $70cm$ distance throughout its length of $1470cm$.

So, the total number of sensors is given by $=1470÷70$.

Here, dividend $=1470$.
Divisor $=70$.

The dividend $1470$ can be written in the expaned form as $1470=1000+400+70$.

So, calculating $=1470÷70$ using the "box method",

Adding the partial quotients, you get the final quotient as: $10+10+1=21$.

So, $1470÷70=21$.

Therefore, the telescope will have $21$ sensors in total throughout its length.