How many 3-to-8 line decoders with an enable input are needed to construct a 6-to-64 line decoder without using any other logic gates?
7
8
9
10
according to me ,only two 3:8 line decode will be used for 6:64 line decode,so only one enable input is sufficient for both decoder,for first it will connected directly and invert for the second one.so only seven will be the right answer
Question asked how many 3x8 decoders with enable line. Here we need total 9, but among those 8 with enable inputs. I think intention of question is to ask this only. In that case answer 8 is correct.