Product of a List Calculator

How it is calculated

The tool splits the text on commas and spaces (any mix of them), checks that every piece is a number, and multiplies them all: P = n₁ × n₂ × … × nk. It shows P and the count k of numbers used. A single number is a valid list and returns itself. If any piece is not numeric, such as a letter or a semicolon-joined pair like 2;3, the whole input is rejected. Use a dot for decimals: because a comma separates items, 2,5 is read as the two numbers 2 and 5, not 2.5. A zero anywhere makes the product 0, and an odd number of negative values makes it negative. Products from 0.01 up to 1 billion print with two decimals. Larger or smaller ones keep 6 significant figures instead: 123456 × 98765 shows as 12,193,100,000, and 0.001 × 0.002 shows as 2 × 10⁻⁶. A product too big to represent gives no result.

Common mistakes

• Typing a decimal comma such as 2,5. The comma is a separator, so this becomes 2 and 5 and the product is 10.00, not 2.5; write 2.5.
• Losing a minus sign. A single missing negative flips the sign of the whole product.
• Leaving a 0 in the list by accident, which makes the whole product 0.00.
• Separating the numbers with semicolons or other symbols. Only commas and spaces are accepted, and anything else makes the input invalid and shows no result.
• Reading a rounded large product as exact. Above 1 billion only the first 6 significant figures are real, so 12,193,100,000 is not the exact 12,193,131,840.