Developmental Mathematics Student Workbook Level 5 Tens Ones Simple Additions and Subtractions Author:L. George Saad Grade 3, Semester 1 - Level 5. Tens & Ones: Simple Additions and Subtractions Level 5. Tens & Ones: Simple Additions and Subtractions covers the concepts and symbols of a tens-and-ones number using adding without grouping and subtracting without exchange.