2048 is a stochastic single-player game involving 16 cells on a 4 by 4 grid,where a player chooses a direction among up, down, left, and right to obtain ascore by merging two tiles with the same number located in neighboring cellsalong the chosen direction. This paper presents that a variant 2048-4x3 12cells on a 4 by 3 board, one row smaller than the original, has been stronglysolved. In this variant, the expected score achieved by an optimal strategy isabout $50724.26$ for the most common initial states: ones with two tiles ofnumber 2. The numbers of reachable states and afterstates are identified to be$1,152,817,492,752$ and $739,648,886,170$, respectively. The key technique isto partition state space by the sum of tile numbers on a board, which we callthe age of a state. An age is invariant between a state and its successiveafterstate after any valid action and is increased two or four by stochasticresponse from the environment. Therefore, we can partition state space by agesand enumerate all (after)states of an age depending only on states with therecent ages. Similarly, we can identify (after)state values by going along withages in decreasing order.