Maharashtra State BoardSSC (English Medium) 6th Standard
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Multiplication of Decimal Numbers

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  • Decimal multiplication through models

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Multiplication of Decimal Numbers:

Let us now learn the multiplication of two decimal numbers.

1) Find 0.1 × 0.1.

Now, 0.1 = `1/10. "So", 0.1 xx 0.1 = 1/10 xx 1/10 = (1xx1)/(10xx10) = 1/100 = 0.01.`

Let us see it’s a pictorial representation,

The fraction `1/10` represents 1 part out of 10 equal parts. The shaded part in the picture represents `1/10`.
We know that, `1/10 xx 1/10 "means" 1/10 "of" 1/10`.

So, divide this `1/10`th part into 10 equal parts and take one part out of it.

Thus, we have,

The dotted square is one part out of 10 of the `1/10`th part. That is, it represents `1/10 xx 1/10 "or"  0.1 xx 0.1`.

There are 100 small squares. So the dotted square represents one out of 100 or 0.01. Hence, 0.1 × 0.1 = 0.01.

2) Find 0.2 × 0.3.

We have, 0.2 × 0.3 = `2/10 xx 3/10`

As we did for `1/10 xx 1/10`, let us divide the square into 10 equal parts and take three parts out of it, to get `3/10`. Again divide each of these three equal parts into 10 equal parts and take two from each.

We get `2/10 xx 3/10`.

The dotted squares represent `2/10 xx 3/10` or 0.2 × 0.3.

Since there are 6 dotted squares out of 100, so they also represent 0.06.

Thus, 0.2 × 0.3 = 0.06.

Example

Multiply 0.1 × 0.1

  0.1
× 0.1
  0 1
+ 0 0 0
  0 . 0 1

Example

Multiply 2.3 × 3.8

  2.3
× 3.8
  184
+ 690
  8.74

Example

Multiply 1.25 × 3.78

  1.25
× 3.78
  1000
+ 8750
+ 37500
  4.7250

Example

The side of an equilateral triangle is 3.5 cm. Find its perimeter.

All the sides of an equilateral triangle are equal.

So, length of each side = 3.5 cm

Thus, perimeter = 3 × 3.5 cm = 10.5 cm

Example

The length of a rectangle is 7.1 cm and its breadth is 2.5 cm. What is the area of the rectangle?

Length of the rectangle = 7.1 cm

Breadth of the rectangle = 2.5 cm

Therefore, area of the rectangle = 7.1 × 2.5 cm2 = 17.75 cm2

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Multiplication of Decimal Numbers [00:17:34]
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