Variable as Placeholder Math Example 4

Follow the full solution, then compare it with the other examples linked below.

Example 4

easy
Find the value of nn in 3n=213n = 21.

Solution

  1. 1
    nn is a placeholder for one number. Divide both sides by 3: n=7n = 7.
  2. 2
    Check: 3(7)=213(7) = 21 ✓

Answer

n=7n = 7
The variable nn stands for a single specific value. Solving the equation reveals what that value is.

About Variable as Placeholder

A variable acts as a placeholder — a letter or symbol (like x, n, or y) that stands in for an unknown or changing number in a mathematical expression or equation. It represents one specific unknown value that satisfies a given condition.

Learn more about Variable as Placeholder →

More Variable as Placeholder Examples

Example 1 easy

In the equation [formula], what specific value does [formula] represent?

Example 2 medium

A rectangle has area 24 cm² and width 4 cm. Use a variable to find the length.

Example 3 medium

Maria has some stickers. After giving away 8, she has 15 left. Write an equation and find how many s

Example 5 medium

I think of a number, double it, and add 5 to get 19. What is my number?

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