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# What is a crossnumber puzzle?

A crossnumber puzzle (also known as crossfigure, figure logic, or numberlock puzzle) looks like a crossword puzzle, but has numbers instead of words in a grid. The crossnumber solver can find all possibilities of filling the grid with numbers in a way that all statements about these numbers are true.

Many number puzzles that do not look like a crossnumber puzzle at first glance can be formulated as crossnumber puzzles and therefore be solved by the crossfigure solver.

Here is an example:

# Logelei by Zweistein

Because in a crossnumber puzzle, we are not looking for words, consisting of letters, but for numbers, the positions of those unknown numbers are marked with letters. No zero occurs in this crossnumber puzzle. A **"Palindrome"** is a number that does not change if its digits are reversed, e. g. 525.

The solution can be found by either evaluating the following statements and thinking hard or by using the crossnumber solver.

**Across**

**A **A down multiplied with the square of the reverse of A down

**G **If J across is subtracted from this number, the result is a square number.

**H **A square number

**I **A across minus D down

**J **A multiple of R across

**K **The sum of this odd number's digits is a prime number.

**M **Product of the digits of I across

**O **Square root of the product of E down's digits

**P **A cubic number

**Q **A prime number

**R **A prime number

**Down **

**A **A prime number

**B **A Palindrome

**C **A Palindrome

**D **A Palindrome

**E **Divisible by N down

**F **Divisible by A down

**I **Divisible by L down

**L **A Palindrome

**N **A prime number