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Fractions and Decimals - Introduction to Decimals (Tenths and Hundredths)

Grade 4IB

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

🔑Concepts

A decimal is a way of writing a fraction whose denominator is a power of ten, such as 1010, 100100, or 10001000. It represents a part of a whole number using a decimal point to separate the whole number part from the fractional part.

The Decimal Point is a dot used to separate the whole number from the fractional part. To the left of the point are the Ones, Tens, and Hundreds; to the right are the Tenths and Hundredths. Visualizing a place value chart, it looks like: [Hundreds] [Tens] [Ones] . [Tenths] [Hundredths].

Tenths represent one part out of ten equal parts of a whole. If you imagine a long rectangular bar divided into 1010 equal vertical strips, shading one strip represents 110\frac{1}{10} or 0.10.1. Ten tenths make one whole: 10×0.1=1.010 \times 0.1 = 1.0.

Hundredths represent one part out of one hundred equal parts of a whole. Imagine a large square grid divided into 10×1010 \times 10 smaller squares (totaling 100100 squares). Shading just one tiny square represents 1100\frac{1}{100} or 0.010.01. One hundred hundredths make one whole: 100×0.01=1.0100 \times 0.01 = 1.0.

The relationship between Tenths and Hundredths is that one tenth is equal to ten hundredths (0.1=0.100.1 = 0.10). Visually, if you look at a hundredths grid, one full column of 1010 small squares is exactly the same size as one bar in a tenths grid.

Decimals can be written as fractions and vice versa. For example, the fraction 710\frac{7}{10} is written as 0.70.7 in decimal form, and the fraction 24100\frac{24}{100} is written as 0.240.24. When writing hundredths, the second digit after the decimal point is the hundredths place.

Placeholders are used when a decimal has no value in a specific position. For example, '3 ones and 5 hundredths' is written as 3.053.05. The 00 in the tenths place is a placeholder to show there are zero tenths.

📐Formulae

Decimal=Whole Number+Tenths10+Hundredths100\text{Decimal} = \text{Whole Number} + \frac{\text{Tenths}}{10} + \frac{\text{Hundredths}}{100}

1 Whole=1010=1001001 \text{ Whole} = \frac{10}{10} = \frac{100}{100}

0.1=110=10100=0.100.1 = \frac{1}{10} = \frac{10}{100} = 0.10

0.01=11000.01 = \frac{1}{100}

a10+b100=0.ab\frac{a}{10} + \frac{b}{100} = 0.ab (where aa and bb are digits)

💡Examples

Problem 1:

Write the fraction 610\frac{6}{10} and 45100\frac{45}{100} as decimals.

Solution:

  1. For 610\frac{6}{10}: Since the denominator is 1010, the digit 66 goes in the tenths place. Result: 0.60.6.
  2. For 45100\frac{45}{100}: Since the denominator is 100100, the digits represent 44 tenths and 55 hundredths. Result: 0.450.45.

Explanation:

To convert fractions with denominators of 1010 or 100100 to decimals, identify the place value. A denominator of 1010 means one decimal place; 100100 means two decimal places.

Problem 2:

Convert the mixed number 531005 \frac{3}{100} into a decimal.

Solution:

Step 1: Identify the whole number part, which is 55. This goes before the decimal point. Step 2: Identify the fractional part, which is 3100\frac{3}{100}. Step 3: Since there are 33 hundredths and no tenths mentioned, place a 00 in the tenths place and a 33 in the hundredths place. Final Answer: 5.035.03.

Explanation:

When there are no tenths in a hundredths fraction, we must use 00 as a placeholder in the tenths column to ensure the 33 stays in the hundredths position.