Signalling

Here are some illustrations:
One Two Three Four

Five Six Seven Eight

Nine Ten Eleven Twelve

Thirteen Fourteen Fifteen Sixteen

Seventeen Eighteen Nineteen Twenty

Twenty-one Twenty-two Twenty-three Twenty-four

One	Two	Three	Four
Five	Six	Seven	Eight
Nine	Ten	Eleven	Twelve
Thirteen	Fourteen	Fifteen	Sixteen
Seventeen	Eighteen	Nineteen	Twenty
Twenty-one	Twenty-two	Twenty-three	Twenty-four