Learning * learning = mathematics, knowing that one digit * one digit = two digits, then this number is at least 4. According to the two digits of the square of a number, only 5 and 6 meet the conditions.

Namely: 5 * 5 = 25, 6 * 6 = 36.

That is, number = 2, then learning = 5 or number = 3, learning = 6.