Skill: Solve problems with missing information

When a problem has missing information, first find what the question is asking for. Then check whether the facts given are enough to find it.

Use these steps:

1. Name the unknown. What number is missing?
2. Find the relationship. Decide whether to add, subtract, multiply, or divide.
3. Write an equation.
4. Solve and check that your answer fits the problem.

Example

There are $(36)$ crayons. They are shared equally among $4$ boxes. How many crayons go in each box?

Step 1: Find the unknown.

We do not know how many crayons are in each box.

Step 2: Choose an operation.

The $(36)$ crayons are split into $4$ equal groups, so we divide:

$$36 \div 4$$

Step 3: Solve.

$$36 \div 4 = 9$$

Step 4: Check.

If each box has $9$ crayons, then:

$$4 \times 9 = 36$$

So, the missing number is $9$ crayons in each box.