Do You Know 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) And Letter 'c' does not appear anywhere in the spellings of entire English Counting