Lesson 22 Part I Warming-up Exercises Training Focus : Identifying numbers with four to six digits Directions : This drill is for practice in writing umbers with four to six digits. For easy reading and writing, numbers of more than four digits are separated by commas into groups of three digits each, for examples, 1,728. Listen carefully. Say the number over to yourself after you hear it. Then write it down as rapidly as you can. A . Numbers: Teens and Tens 1 . The student from Norway bought (40----14) books.