JAMB 1991 · UME · Q2

Number bases

If 2257 is the result of subtracting 4577 from 7056 in base $n$ , find $n$ .

Worked solution (try it first)

Check by adding: $2257 + 4577$ must give $7056$ in base $n$ .
Units column: $7 + 7 = 14$ is written as 6 carry 1, so $14 = n + 6$ .
So $n = 8$ , option A.
The other columns agree: $5 + 7 + 1 = 13 = 8 + 5$ , and so on.

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