Math Buffs: I bet you didn’t know this

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...