Base Ten Operations
GradesFifth GradeBase Ten OperationsFour Operations with Decimals

Four Operations with Decimals

🔟 Base Ten Operations
💯

Four Operations with Decimals

Decimals follow the same rules — just watch that point!

Adding, subtracting, multiplying, and dividing decimals uses the same algorithms as whole numbers. The key rule for adding and subtracting: always line up decimal points. For multiplication, count decimal places. For division, move the decimal to make the divisor a whole number.

Add/Subtract Decimals

Line up decimal points verticallyAdd zeros as placeholders if neededBring the decimal point straight down

Multiply Decimals

Ignore decimals and multiply as whole numbersCount total decimal places in both factorsPlace decimal point that many places from the right in product

For division: multiply both dividend and divisor by the same power of 10 to eliminate the decimal in the divisor.

🛒Decimal Multiplication
3.4 × 2.5: Multiply 34 × 25 = 850. Total decimal places: 1 + 1 = 2. Answer: 8.50 = 8.5
💡

Remember This!

A quick estimate helps check decimal placement. 3.4 × 2.5 ≈ 3 × 3 = 9. Our answer 8.5 is close to 9 — the decimal is in the right place!

✏️ Try It!

What is 4.2 × 3.1?

Practice with CalcVerse
🔄Fraction ↔ Decimal ↔ %
Take Quiz 📝 — 25 Questions