Theme 8.  Adding and subtracting by ones and in parts

In the theme you learn:
• You will learn ways to add and subtract by ones and in parts;
• You will practice calculating expressions using ways to add and subtract by ones and in parts;
• You will improve your skills to write a short note and solve problems about increasing a number by a few units and comparing numbers by difference;
• You will practice finding true inequalities among the given ones.