Decimals are numbers that show parts of a whole. The decimal point separates whole numbers from parts less than one.
The place of each digit matters! Digits to the right of the decimal point show tenths, hundredths, and thousandths.
When you add or subtract decimals, always line up the decimal points so each place value matches correctly.
Adding zeros can help line up place values. For example, 1.7 can be written as 1.70 before adding or subtracting.
To multiply decimals, ignore the decimal points and multiply as if they were whole numbers. Then count and place the decimal point in your answer.
Estimate first! 0.6 × 0.4 is close to 0.5 × 0.5 = 0.25, which helps check if your answer makes sense.
When dividing by a decimal, make the divisor a whole number by moving the decimal point. Move the decimal point in the dividend the same number of places.
Check your work by multiplying your quotient by the divisor. The result should be equal to the dividend.
Decimals are used in money, measurement, and science to show precise values. Understanding how to operate with decimals helps solve everyday problems.
Whenever you use decimals, estimate first to see if your answer is reasonable. This is a smart math habit!