Step 1: Multiply as Whole Numbers

Ignore the decimal points and multiply the numbers as if they were whole numbers.

2: Count Decimal Places

Add up the number of decimal places in both numbers you are multiplying.

3: Place the Decimal Point

Starting from the right of your answer, count leftwards the same number of places you found in step 2.

Example 1: 4.52 × 1.3

Step 1: Multiply as whole numbers

$452 \times 13 = 5,876$

Step 2: Count decimal places

• 4.52 has 2 decimal places
• 1.3 has 1 decimal place
• Total = 2 + 1 = 3 decimal places

Step 3: Place the decimal point

Count 3 places from the right of 5,876:

$5.876$

Answer: $4.52 \times 1.3 = 5.876$

Example 2: 0.11 × 1.1

Step 1: Multiply as whole numbers

$11 \times 11 = 121$

Step 2: Count decimal places

• 0.11 has 2 decimal places
• 1.1 has 1 decimal place
• Total = 2 + 1 = 3 decimal places

Step 3: Place the decimal point

Count 3 places from the right of 121:

$0.121$

Answer: $0.11 \times 1.1 = 0.121$

Example 3: 100.55 × 0.2

Step 1: Multiply as whole numbers

$10055 \times 2 = 20,110$

Step 2: Count decimal places

• 100.55 has 2 decimal places
• 0.2 has 1 decimal place
• Total = 2 + 1 = 3 decimal places

Step 3: Place the decimal point

Count 3 places from the right of 20,110:

$20.110$

Answer: $100.55 \times 0.2 = 20.11$

Remember: Zeros at the end of a decimal after the last non-zero digit do not change the value. So 20.110 is the same as 20.11.

Example: 155.25 × 20

Bakari sells 155.25 litres of water daily. How many litres will he sell in 20 days?

Step 1: Multiply as whole numbers

$15525 \times 20 = 310,500$

Step 2: Count decimal places

• 155.25 has 2 decimal places
• 20 is a whole number (0 decimal places)
• Total = 2 + 0 = 2 decimal places

Step 3: Place the decimal point

Count 2 places from the right of 310,500:

$3,105.00$

Answer: 3,105 litres

Example: 327.435 × 7

Step 1: Multiply as whole numbers

$327435 \times 7 = 2,292,045$

Step 2: Count decimal places

• 327.435 has 3 decimal places
• Total = 3 decimal places

Step 3: Place the decimal point

Count 3 places from the right:

$2,292.045$

Answer: $327.435 \times 7 = 2,292.045$

• Multiply the numbers ignoring decimal points
• Add up decimal places from both numbers
• Count that many places from the right of your answer to place the decimal point

In Tanzania, multiplication of decimals is useful when shopping at the market or in shops. For example, if a piece of cloth costs TSH 3,250.50 per metre and Amina buys 2.5 metres for sewing a dress, she multiplies $3,250.50 \times 2.5$ to find the total cost of TSH 8,126.25. This skill helps with budgeting, buying food, and running small businesses.