Did you know A B C D very well?

Still, I bet you didn't know this... Letters 'a', 'b', 'c' & ’d’ do not appear anywhere in the spellings of 1 To 99 Letter ’d’ comes for the first time in Hundred Letters 'a', 'b' & 'c' do not appear anywhere in the spellings of 1 to 999 Letter 'a' comes for the first time in thousand Letters 'b' & 'c' do not appear anywhere in the spellings of 1 to 999,999,999 Letter 'b' comes for the first time in Billion & Letter 'C' does not appear anywhere in the spellings of entire English Counting