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Solution

Each cube side $a = \sqrt[3]{64} = 4\ \text{cm}$. When joined end to end, dimensions of cuboid $= 8 \times 4 \times 4$. Surface area $= 2(lb + bh + hl) = 2(8\times4 + 4\times4 + 4\times8) = 2(32 + 16 + 32) = 160\ \text{cm}^2$.