Decimals

Summary and Exam Tips for Decimals

Decimals is a subtopic of Numbers, which falls under the subject Mathematics in the IB MYP curriculum. Understanding decimals involves mastering operations such as addition, subtraction, multiplication, and division, as well as converting between fractions and decimals.

• Addition of Decimals: Align decimal points and add from right to left, similar to whole numbers. Example: $0.64 + 12.867 + 2.2 = 15.707$.
• Subtraction of Decimals: Align decimal points and subtract from right to left, just like whole numbers. Example: $10.96 - 3.657 = 7.303$.
• Multiplication of Decimals: Multiply as whole numbers, then place the decimal in the product according to the total decimal places in the factors. Example: $2.34 \times 2 = 4.68$.
• Division of Decimals: Divide as with whole numbers, placing the decimal point in the quotient directly above the dividend's decimal. Example: $36.4 \div 14 = 2.6$.
• Conversion between Fractions and Decimals: Convert fractions with denominators of 10, 100, or 1000 to decimals and vice versa. Example: $\frac{3}{5} = 0.6$ and $0.75 = \frac{3}{4}$.

Exam Tips

• Align Decimal Points: Always ensure decimal points are aligned vertically when adding or subtracting decimals to avoid errors.
• Count Decimal Places: In multiplication, count the total decimal places in the factors to correctly place the decimal in the product.
• Directly Above: When dividing, place the decimal point in the quotient directly above the decimal in the dividend for accuracy.
• Practice Conversions: Regularly practice converting between fractions and decimals to become proficient in both directions.
• Check Work: Double-check your calculations, especially the placement of decimal points, to ensure accuracy in your answers.