# Cube Root Practice

The cube root of
123456789
= ?

Explanation of what's going on.

## Explanation

The purpose of this interactive page is to practice the technique described in my blog article How to Do Cube Roots of 9 Digit Numbers in Your Head.

## Instructions

• The number shown is the cube of a randomly selected 3 digit number (i.e. from 100 to 999).
• Click on any one of the squares to the right of where it says "Answer:", and then you can enter a digit of the answer (by typing it).
• You can use backspace or delete to delete a digit, and you can use left and right arrow keys to move from one digit position to another. (Note: the backspace and delete keys don't work in Opera.)
• When you have entered all three digits, you will get either a congratulatory message, if you were right, or you will get an explanation of what you did wrong.
• Even after finishing, you can continue to update the digits (for example to see what happens if you correct a wrong digit).
• Or, you can press the "Try New Cube Root" button to start again with a new number.