42797 KB will take 85512 sectors (42797*1024 bytes/512 bytes) Since, there are 64 sectors per surface 85512/64 *1337 406 sectors are required, so we take 1338 sectors These sectors are distributed among 16 surfaces, so 1338/16 * 8358 cylinders will be required So, the final answer will be 84 + 1200 = 1284. One more fact to be noted is that the file occupies 83.58 cylinders, but the 0 58 cannot be accommodated in the first one (the files storage starts from < 1200.9, 40 >). Hence, the file will be extended to 194 (85594 - 85400) more bytes of cylinder 1284