Since both learning and thinking (multiplicand and multiplier) are two digits, the group with the smallest product should be 12*37=444, which means at least 444.

Considering that the single digits of learning thinking and thinking are the same, thinking may be 7 or 4 (single digits of 74). As mentioned above: 12*37=444, so 444 can't be 74 times the number of 12.

So Si = 7,37 * 27 = 999.