(B)12 + (BB)12 + (BBB)12 + (BBBB)12 = (…………..)10
Explanation:
(B)12 = 11 × 1 = 12 – 1.
(BB)12 = 11 × 12 + 11 = 122 - 1.
(BBB)12 = 11 × 122 + 11 × 12 + 11 = 123 - 1.
… and so on
∴ (B)12 + (BB)12 + (BBB)12 + (BBBB)12 = (12 - 1) + (122 - 1) + (123 - 1) + (124 - 1).
= (12 + 122 + 123 + 124) – 4 = 22616.
Hence, 22616.
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