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Grade 4 Math · World 2: Big Number Bridge · Level 18
A Letter for the Unknown
Write and solve equations like n + 12,450 = 30,000.
Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.
What children learn in Level 18
- A letter can stand for a number we don't know yet. In n + 12,450 = 30,000, n is the missing part.
- To find n, think: 12,450 plus what makes 30,000? Or subtract: 30,000 minus 12,450 is 17,550. So n = 17,550.
- Check by putting it back: 17,550 plus 12,450 is 30,000. It works! That shows your answer is right.
Georgia's K-12 Mathematics Standards:
- 4.NR.2.1 — Fluently add and subtract multi-digit numbers to solve practical, mathematical problems using place value understanding, properties of operations, and relationships between operations.
- 4.NR.2.5 — Solve multi-step problems using addition, subtraction, multiplication, and division involving whole numbers. Use mental computation and estimation strategies to justify the reasonableness of solutions.