Last week we discussed cubes, this week let us go one step further and discuss cube roots. Just like in squares, it is first important to know the cubes table for numbers 1 to 10. If we know this we can calculate the cube root of the perfect cube number mentally just by looking at the number. So let us first get familiar with the cube of the first ten numbers from the table below:
We can deduce the following points from this:
units digit will have 1 as the units digit in its cube.
number in the units place in the cube.
One special fact about a cube is that the digit sum of a perfect cube will be 1, 8 or 9. This fact can be used to check whether a number is a perfect cube or not.
Let us check whether the following numbers are perfect cubes or not.
Consider 79507
Consider 17562
What will be in the unit’s digit of the cube of 36?
What can you say about the units digit of the cube of 87?
Now check which of these may be a perfect cube?
456533
42876
238328
157466
Tip of the week: Understanding concepts will helps us to solve any problem.