Equal decimals

### 1.1. Knowledge to remember

a)** For example:** 9dm = 90cm

Which: 9dm = 0.9m

should: 0.9m = 0.90m

So 0.9 = 0.90 or 0.90 = 0.9

**b)** If you add zero to the right of the decimal part of a decimal, you get a decimal equal to it

**For example: **0.9 = 0.90= 0.900= 0.9000

8.75 = 8,750= 8.7500 = 8,75000

If a decimal number has a zero to the right of the decimal, then removing the zero will give you a decimal equal to it.

**For example:** 0.9000 = 0.900 = 0.90 = 0.9

8,750000 = 8,75000 =8.7500 = 8,750= 8.75

### 1.2. Solution of textbook exercises page 40

**Lesson 1 of the textbook page 40:**

Remove the leading zeros to the right of the decimal to get decimals written in a more compact form:

a) 7,800; 64,9000; 3,0400

b) 2001,300; 35.020; 100.0100

*Solution guide:*

a) 7,800=7.80=7.8

64,9000=64,900=64,90=64.9

3.0400=3.040=3.04

b) 2001,300=2001,30=2001.3

35.020=35.02

100,0100=100,010=100.01

Lesson 2 Textbook page 40:

Add the digits 00 to the right of the decimal places of the following decimals so that their decimal parts have the same number of digits (all three digits):

a) 5,612 17.2 480.59

b) 24.5 80.01 14.678

*Solution guide:*

a) 5,612 17.2=17,200 480.59=480,590

b) 24.5=24.5 80.01=80,010 14.678

Lesson 3 Textbook page 40:

When writing the decimal number 0,1000,100 as a decimal fraction, Lan writes: \(0,100 = \frac{{100}}{{1000}}\); American friends write \(0,100 = \frac{{10}}{{100}}\); Hung wrote: \(0,100 = \frac{{1}}{{100}}\). Who wrote it right, who wrote it wrong? Why?

*Solution guide:*

Since \(0,100 = \frac{{100}}{{1000}}\) Lan is correct

\(0,100 = 0.10 = \frac{{10}}{{100}}\) so the US is correct

\(0,100 = 0.1 = \frac{{1}}{{10}}\) so Hung is wrong

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