Operations on Decimals
Learning to add, subtract, multiply and divide decimal numbers.
Core concept
When multiplying decimals, first multiply the numbers as if they were whole numbers (ignoring decimal points), then count the total number of decimal places in both original numbers and place the decimal point that many places from the right in the answer. When dividing by a decimal, both the divisor and dividend can be multiplied by a power of 10 to make the divisor a whole number, simplifying the division process while keeping the final answer mathematically correct.
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• Add/subtract decimals by aligning decimal points carefully.
• To multiply decimals: multiply as whole numbers, then place the decimal point based on total decimal places.
• To divide by a decimal: convert the divisor to a whole number by multiplying both numbers by a power of 10.
• These rules ensure decimal operations give mathematically correct results.