Cube Root of Any Number in 5 seconds - Crazy Math Trick

Added: 2026-05-19

[00:00:00]We all know how to find cube roots of perfect cubes very easily. For example, the cube root of 27 is 3 and the cube root of 64 is 4. But the real challenge begins when the number is not a perfect cube. If someone asks you the cube root of a number like 29 or 131, most people would struggle to answer quickly.

[00:00:24]So in this video, we are going to learn a very simple and powerful trick to find approximate cube roots of non-perfect cube numbers within seconds. Suppose we want to find cube root of 29.

[00:00:38]The first thing we notice is that 27 is very close to 29 and we already know that the cube root of 27 is 3.

[00:00:47]So we begin with 3 as our base value.

[00:00:50]Since 29 is greater than 27, we will add a correction term, which will be a fraction.

[00:00:57]The difference between 29 and 27 is 2.

[00:01:00]So we place 2 in the numerator and multiply it with the cube root value, which is 3.

[00:01:07]Now, in the denominator, we write 3 multiplied by this same number 27.

[00:01:13]That's it.

[00:01:15]After calculation, the answer comes out to be approximately 3.07, which is extremely close to the actual cube root of 29. That was simply mind-blowing. Now let us take another example. Cube root of 59. This time, the nearest perfect cube is 64, whose cube root is 4.

[00:01:38]Since 59 is smaller than 64, so for the correction term, we will use subtraction instead of addition.

[00:01:47]Now the difference between 64 and 59 is 5. So we write 5 in the numerator and multiply it with this 4. Then in the denominator, we again write three multiplied by this 64.

[00:02:02]After calculation, the answer comes out around 3.89, which matches the actual cube root quite well.

[00:02:11]That is simply beautiful.

[00:02:13]Let us try one final example.

[00:02:16]Suppose we want to find the cube root of 129.

[00:02:20]The nearest perfect cube is 125, whose cube root is five.

[00:02:26]Since 129 is larger than 125, we use a plus sign.

[00:02:33]The difference between them is four, so we multiply four with five and divide by 3 * 125.

[00:02:41]This gives an approximate answer of 5.05, which is again very close to the true value.

[00:02:49]Now, it is your turn to practice. Try solving a few cube root questions using this method, and let me know your answers in the comments.

[00:02:59]Like, share, and subscribe. So good.

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