Decimals are multiplied in the same way as whole numbers.
Multiply 5 × 1.1.
Step 1: Ignore the decimal point and multiply as if both factors are whole numbers.
Step 2: Count the number of decimal places after the decimal point in both factors.
5 has 0 decimal places. 1.1 has 1 decimal place. There is 1 decimal place in total.
Step 3: The total number of decimal places in the factors tells the number of decimal places in the product. Count one decimal place from the right. Place the decimal point in the answer.
5 × 1.1 = 5.5
Be careful to avoid careless answers when doing easy questions. Focus on each problem. Don’t be in a hurry.
Multiply 4.7 × 0.02.
Step 1: Write the factors in a column. You do not need to line up the decimal points.
Step 2: Ignore the decimal point and multiply as if both factors were whole numbers. Treat 0.02 as the whole number 2.
Step 3: Count the number of decimal places in both factors.
4.7 has 1 decimal place. 0.02 has 2 decimal places. There are 3 decimal places in total.
Step 4: Count 3 decimal places from the right. There are only 2 decimal places in the product. Add a zero to the left to place the decimal point. Use a zero as a place holder in the ones place.
Remember to include the units in your answers. Area problems always have square units.