Do you know --(@

Its lesson time - Did you know? Letters 'a', 'b', 'c' and 'd' do not appear anywhere in the spellings of 1 to 99.

Letter 'd' comes for the first time in Hundred.

Letters 'a', 'b' and 'c' do not appear anywhere in the spellings of 1 to 999.

Letter 'a' comes for the first time in Thousand.

Letters 'b' and '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 of numerics.