OpenOlympiad
Concept 10 of 11Foundation
Video

Adding, subtracting, multiplying decimals

Adding / subtracting: line up the decimal points carefully, then add or subtract as usual. Fill missing places with zeros.

Multiplying: ignore the decimal points, multiply the numbers, then place the decimal so the answer has as many decimal places as the TOTAL in the two numbers.

Dividing: shift decimal points in both numbers so the divisor becomes a whole number; then divide normally.

Example
Add 2.3 + 1.47: line up → 2.30 + 1.47 = 3.77.
0.2 × 0.3: ignore dots → 2×3=6. Total decimals = 1+1=2 → 0.06.
1.5 ÷ 0.3: shift → 15 ÷ 3 = 5.
💡 Tip:Write zeros to align place values. 2 + 0.47 ≠ 2.47 only if you've lined up correctly (it IS 2.47 when aligned).
Prefer a video? Open YouTube search for “decimal operations class 6

🎯 Try it!

5 questions to check what you just read.

0 / 5
  1. Q1.2.5 + 1.75 = ?
  2. Q2.0.6 × 0.3 = ?
  3. Q3.5 − 1.7 = ?
  4. Q4.1.5 ÷ 0.3 = ?
  5. Q5.0.4 × 10 = ?