Suppose 1 chocolate costs Rs 100

How much would 5 chocolate cost?

Cost of 1 Chocolate = Rs 100

Cost of 5 Chocolate = Rs 5 × 100

=
**
Rs
**
**
500
**

Let’s take another example

####
**
Suppose 5 pens cost
**
**
Rs
**
**
100. How would 9 pen cost?
**

**
**

Cost of 5 pens = Rs 100

Cost of 1 pen = Rs 100/5

Cost of 9 pens = Rs 9 × 100/5

= 9 × 20

=
**
Rs
**
**
180
**

So,

What we did was,

We find cost of 1 pen, & then find cost of 9 pens

This method of finding value of 1 unit

& then using it to find value of multiple units is called
**
Unitary Method.
**

Let’s take another example

####
**
Three watches cost
**
**
Rs
**
**
1200. How much five watches would cost?
**

**
**

Cost of three watches = Rs 1200

Cost of one watch = Rs 1200/3

Cost of five watches = Rs 1200/3 × 5

= 400 × 5

=
**
Rs
**
**
2000
**

####
**
5 identical books weights 5 kg. How much 3 of these books weight?
**

**
**

Weight of 5 identical books = Rs 5 kg

Weight of 1 books = 5/5 kg

Weight of 1 books = 5/5 kg × 3 kg

= 1 × 3

=
**
3 kg
**

####
**
A train takes 3 hours to travel 180 km. How much time would it take to travel 540 km?
**

Time taken to travel 180 km = 3 hours

Time taken to travel 1 km = 3/180 hours

Time taken to travel 540 km = 3/180 × 540 hours

= 3/18 × 54 hours

3/6 × 54 hours

=
**
9 hours
**