To multiply decimals, you mostly use the same steps as multiplying whole numbers, then fix the decimal point at the end.

Quick Scoop

Core idea

  • Multiply the numbers as if they don’t have decimal points.
  • Then count how many total digits are after the decimal in the numbers you started with.
  • Put the decimal in your answer so it has that same number of digits after the decimal.

Step‑by‑step method (with examples)

1. Decimal × whole number

Example: 3.4×63.4\times 63.4×6

  1. Ignore the decimal: do 34×6=20434\times 6=20434×6=204.
  1. The original decimal 3.4 has 1 digit after the decimal.
  1. So the answer must have 1 digit after the decimal → 20.4.

Another example: 1.74×131.74\times 131.74×13

  • Think of 1.74 as 174, multiply: 174×13=2262174\times 13=2262174×13=2262.
  • 1.74 has 2 digits after the decimal, 13 has 0, total = 2.
  • Move the decimal 2 places from the right: 22.62.

2. Decimal × decimal

Example: 0.2×0.40.2\times 0.40.2×0.4

  1. Ignore decimals: 2×4=82\times 4=82×4=8.
  1. Count decimal digits: 0.2 has 1 digit, 0.4 has 1 digit → total 2.
  1. Answer needs 2 digits after decimal → 0.08 (so write 8 as 0.08).

Example: 2.32×1.52.32\times 1.52.32×1.5

  1. Multiply as whole numbers: 232 × 15 = 3480.
  1. Count decimal places: 2.32 has 2, 1.5 has 1 → total 3.
  1. Move decimal 3 places from the right in 3480 → 3.480 = 3.48.

3. Multiplying by 10, 100, 1000, …

There’s a shortcut with powers of 10.

  • Multiply by 10 → move the decimal one place to the right.
  • Multiply by 100 → move it two places to the right.
  • Multiply by 1000 → move it three places to the right, and so on.

Examples:

  • 2.32 × 10 = 23.2
  • 2.32 × 100 = 232
  • 2.32 × 1000 = 2320
  • 0.0023 × 100 = 0.23
  • 0.1 × 1000 = 100

Mini table of examples

[3][1] [9][1] [5][1] [3][9] [3][9] [3] [1][9] [9][1] [5][1] [1][5] [7][1] [7][1]
Problem Whole‑number product Total decimal digits Final answer
3.4 × 6 34 × 6 = 204 1 20.4
1.74 × 13 174 × 13 = 2262 2 22.62
0.2 × 0.4 2 × 4 = 8 2 0.08
2.32 × 100 — (move decimal) Move 2 places right 232

A quick “story” way to remember

Imagine you hide the decimal points under a cover, do a normal multiplication, then bring them back at the end.

Count how many “little digits” were hiding to the right of all decimals together, and that count tells you where to place the decimal in your final answer.

Common mistakes to avoid

  • Lining up decimals like in addition or subtraction; for multiplication, you don’t need to line up decimal points.
  • Forgetting to count decimal places in both numbers.
  • Not adding extra zeros if the product is too short (for example, turning 8 into 0.08 by adding a zero).

Tiny practice set

Try these yourself (answers follow the same rules above).

  1. 4.5 × 0.2
  2. 0.06 × 0.3
  3. 7.25 × 100
  4. 0.9 × 0.9

If you tell me your answers, I can check them and show every step. TL;DR: Multiply like whole numbers, then place the decimal in the product so it has as many decimal digits as the two starting numbers combined.

Information gathered from public forums or data available on the internet and portrayed here.