JAMB - Mathematics (2010 - No. 21)
Find r, if 6r7\(_8\) = 511\(_9\)
3
2
6
5
설명
6r7\(_8\) = 511\(_9\)
6 x 8\(^2\) + r x 8\(^1\) + 7 x 8\(^0\) = 5 x 9\(^2\) + 1 x 9\(^1\) + 1 x 9\(^0\)
6 x 64 + 8r + 7 x 1 = 5 x 81 + 9 + 1 x 1
384 + 8r + 7 = 405 + 9 + 1
8r = 415 - 391
8r = 24
r = \(\frac{24}{8}\)
= 3