Find r, if 6r7\(_8\) = 511\(_9\)

Evaluate \(1011_{two}\) + \(1101_{two}\) + \(1001_{two}\) - \(111_{two}\)

What is the Value of 11101\(_{two}\)+ 10011\(_{two}\) - 10001\(_{two}\)?

Subtract 16418\(_9\) from 18630\(_9\).

Evaluate (212)\(_3\) - (121)\(_3\) + (222)\(_3\)