
Work with addition and subtraction equations.
8. Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example,
determine the unknown number that makes the equation true in each of the equations 8 += 11, 5 =– 3, 6 + 6 =.


Solve problems involving the four operations, and identify and explain patterns in arithmetic.
Solve twostep word problems using the four operations. Represent these problems using equations with a letter standing
for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies
including rounding.32


