Question

The number `100` is written on the board. Find a digit that satisfies the following condition:

If we add it to the notation of the number written on the board once to the left and once to the right, we get a number that is divisible by `12`.

Difficulty level (1 very easy - 10 very hard): 2

Arithmetic Number Theory -> Modular Arithmetic / Remainder Arithmetic -> Divisibility Rules -> Divisibility Rules by 2, 4, and 8 Number Theory -> Modular Arithmetic / Remainder Arithmetic -> Divisibility Rules -> Divisibility Rules by 3 and 9 Number Theory -> Prime Numbers -> Prime Factorization

Sources:

problems.ru web site

ליאל - 4 years ago

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