A Letter for the Unknown

Solve n ÷ 6 = 125 and 8 × p = 2,400.

Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.

What children learn in Level 38

A letter can stand for an unknown number. In n divided by 6 equals 125, n is the whole we're sharing.
Multiplying undoes dividing: 6 groups of 125 is 6 times 125, which is 750. So n is 750.
In 8 times p equals 2,400, divide: 2,400 divided by 8. 24 hundreds divided by 8 is 3 hundreds, so p is 300.
Check by putting it back in: 8 times 300 is 2,400. It works!

Georgia's K-12 Mathematics Standards:

4.NR.2.4 — Solve authentic division problems involving up to 4-digit dividends and 1- digit divisors (including whole number quotients with remainders) using strategies based on place-value understanding, properties of operations, and the 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.