19. BEDDING OUT
I bought less than 100 plants for my new rosery, and found that if I set them 3 in a row there would be one over; if 4 in a row there would be two over; if 5 in a row, three over; and if 6 in a row, four over. How many rose trees did I buy?
20.
Can you arrange three nines so that they represent exactly 20?
21.
A house has nine windows on its front. How many signals can be given by merely leaving one or more of them open?