This math topic focuses on finding missing values in addition equations involving two-digit numbers. Learners practice solving problems where either addend or the sum is unknown. Examples include equations like "71 + ? = 157" and "? + 73 = 153." The equations belong to a broader unit on the addition and subtraction of integers using one and two-digit numbers. Each question offers multiple-choice answers to assess understanding and strengthen integer operation skills.

Work on practice problems directly here, or download the printable pdf worksheet to practice offline.