There is a unique number of ten digits, for which the following holds:

• all digits from 0 up to 9 occur exactly once in the number;
• the first digit is divisible by 1;
• the number formed by the first two digits is divisible by 2;
• the number formed by the first three digits is divisible by 3;
• the number formed by the first four digits is divisible by 4;
• the number formed by the first five digits is divisible by 5;
• the number formed by the first six digits is divisible by 6;
• the number formed by the first seven digits is divisible by 7;
• the number formed by the first eight digits is divisible by 8;
• the number formed by the first nine digits is divisible by 9;
• the number formed by the ten digits is divisible by 10.

The question: Which number is this?

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The answer: Click here!

Another question: There is a unique number of which the square and the cube together use all digits from 0 up to 9 exactly once. Which number is this?

Another answer: Click here!

Yet another question: We are looking for a prime number of ten digits, in which all digits from 0 up to 9 occur exactly once. The number may not start with 0. Which number is this?

Yet another answer: Click here!

The fourth question: We are looking for a number of three digits. It is divisible by both 9 and 11, and when the first and the last digit are interchanged, you get a number which is only two-ninth of the number we are looking for. Which number is this?

The fourth answer: Click here!