There are forty-seven different kinds of kangaroos . The smallest kangaroos are about a quarter of a meter long; the biggest are taller than a man. Kangaroos have very long strong back legs. These are used for jumping. They also have long strong tails used for resting on. Kangaroos' front legs are much shorter, and are almost  like arms. Kangaroos' heads are quite small, but their ears are quite large. Mother kangaroos have a pocket at the front. They have one baby each year. When it is born, the baby kangaroo is straight  into its mother's pocket. The baby kangaroos stay there for six months. The biggest kangaroos stand more than 2 meters tall, and their legs are so strong that they can jump more than 9 meters. They are very fast, and can travel at more than 50 kilometers an hour. They are very strong, but only eat fruit, leaves and grass. How many different kinds of kangaroos are there?
37. 74. 47. 40.