📖Definition
A decimal is a way of writing numbers that are not whole, using a decimal point to separate the whole number part from the fractional part. Each digit after the decimal point represents a fraction of ten (tenths, hundredths, thousandths, etc.).
📐Formula
In the number 3.456: 3 is in the ones place, 4 is in the tenths place (4/10), 5 is in the hundredths place (5/100), and 6 is in the thousandths place (6/1000).
📝Step-by-Step Guide
Understanding Place Value
Each position after the decimal point represents a power of ten: tenths (1/10), hundredths (1/100), thousandths (1/1000), etc.
Adding and Subtracting Decimals
Line up the decimal points, then add or subtract as with whole numbers.
Multiplying Decimals
Multiply as with whole numbers, then count total decimal places in both factors and place the decimal point.
Dividing Decimals
Move the decimal point in the divisor to make it a whole number, move it the same number of places in the dividend, then divide.
⚠️Common Mistakes to Avoid
- Not lining up decimal points when adding or subtracting
- Miscounting decimal places when multiplying
- Forgetting to move the decimal point in division
- Confusing place values (tenths vs hundredths)
- Dropping trailing zeros when they are significant
✏️Practice Problems
Calculate 3.5 + 2.7
Answer: 6.2
Calculate 4.56 × 2.3
Answer: 10.488
Calculate 15.75 ÷ 2.5
Answer: 6.3
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