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Decimals - Place Value in Decimals

Grade 4ICSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

Understanding Decimals: A decimal number consists of a whole number part and a fractional part separated by a dot called the decimal point. For example, in 12.512.5, 1212 is the whole number and .5.5 represents the part of a whole.

The Tenths Place: When one whole is divided into 1010 equal parts, each part is called one-tenth. Visually, imagine a rectangular bar divided into 1010 equal vertical strips; shading one strip represents 110\frac{1}{10} or 0.10.1. It is the first digit to the right of the decimal point.

The Hundredths Place: When one whole is divided into 100100 equal parts, each part is called one-hundredth. Visually, imagine a large square grid made of 1010 rows and 1010 columns (total 100100 small squares); shading one tiny square represents 1100\frac{1}{100} or 0.010.01. It is the second digit to the right of the decimal point.

Place Value Chart: To the left of the decimal point, we have Ones, Tens, and Hundreds. To the right, we have Tenths (110\frac{1}{10}) and Hundredths (1100\frac{1}{100}). Moving one place to the right divides the value by 1010, while moving one place to the left multiplies it by 1010.

Reading Decimals: We read the whole number part normally, say 'point' for the decimal, and then read each digit to the right individually. For example, 4.754.75 is read as 'Four point seven five' or 'Four and seventy-five hundredths'.

Expanded Form: Decimals can be broken down into the sum of the values of their digits. For example, 6.346.34 is written as 6+310+41006 + \frac{3}{10} + \frac{4}{100} or 6+0.3+0.046 + 0.3 + 0.04.

Equivalent Decimals: Adding zeros to the right of the last digit in a decimal does not change its value. For instance, 0.50.5 is the same as 0.500.50, which can be visualized as 55 tenths of a bar being the same area as 5050 hundredths of the same bar.

📐Formulae

1 Tenth=110=0.11 \text{ Tenth} = \frac{1}{10} = 0.1

1 Hundredth=1100=0.011 \text{ Hundredth} = \frac{1}{100} = 0.01

Value of Tenths digit=digit×110\text{Value of Tenths digit} = \text{digit} \times \frac{1}{10}

Value of Hundredths digit=digit×1100\text{Value of Hundredths digit} = \text{digit} \times \frac{1}{100}

1 Whole=10 Tenths=100 Hundredths1 \text{ Whole} = 10 \text{ Tenths} = 100 \text{ Hundredths}

💡Examples

Problem 1:

Write the place value of the underlined digit in the number 25.8725.8\underline{7}.

Solution:

  1. Identify the position: The digit 77 is the second digit to the right of the decimal point. \n2. Name the place: The second place to the right is the Hundredths place. \n3. Calculate the value: 7×1100=7100=0.077 \times \frac{1}{100} = \frac{7}{100} = 0.07.

Explanation:

The digit 77 occupies the hundredths position, meaning it represents 77 parts out of 100100 equal parts of a whole.

Problem 2:

Convert the fraction 491004 \frac{9}{100} into a decimal and write it in expanded form.

Solution:

  1. Decimal Conversion: 49100=4.094 \frac{9}{100} = 4.09 (We use 00 in the tenths place because there are no tenths). \n2. Expanded Form (Fractions): 4+010+91004 + \frac{0}{10} + \frac{9}{100}. \n3. Expanded Form (Decimals): 4+0.0+0.094 + 0.0 + 0.09.

Explanation:

To write the decimal, the whole number 44 goes before the point. Since the fraction is 9100\frac{9}{100}, the 99 must be in the hundredths place, requiring a placeholder zero in the tenths place.