This document provides a method for solving cube roots quickly using a simple table. It explains that the last digit of the cube of numbers 0, 1, 4, 5, 6, and 9 is the same as the original number, while the last digits of the cubes of 2 and 8 are swapped, and the last digits of the cubes of 3 and 7 are swapped. It then demonstrates how to use this table to find the cube root of a number by ignoring the last 3 digits, finding the closest cube to the remaining digits, and using the last digit to determine the final digit of the answer. Several examples are worked through to illustrate the method.
2. How can I solve cube roots ??
To solve the problem of cube roots, you just have to learn
a simple table -
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3. Number Cube Last Digit
1 1 1
2 8 8
3 27 7
4 64 4
5 125 5
6 216 6
7 343 3
8 512 2
9 729 9
10 1000 0
Learn this table & Solve Problems Quickly
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4. Now Note how the last digit of the cubes for 0, 1, 4, 5, 6, and 9 end with the original number.
Note how the last digits for the cubes of 2 and 8 are swapped.
Note how the last digits for the cubes of 3 and 7 are swapped.
Same numbers are
1,4,5,6,9,0
Swapped numbers are =
2,3,7,8
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5. How to find Cube Root
Ignore the last three digits of the number called out by the spectator and choose the memorized cube which is
just lower (or equal) to the remaining number.
The cube root of this is the first digit of your answer.
Now consider the last digit of the number called out by the spectator.
This will indicate the last digit of your answer.
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6. Look at the last digit = 4
Now ignore the last 3 digits = 39304
Now find the closest cube of remaining digit (39)
27 < 39 < 64
So we will take the cube of 3 which is 27. (Lower cube)
The answer is
𝟑
𝟑𝟗𝟑𝟎𝟒 = 𝟑𝟒
Que 1. - Find the cube root of 39304 -
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7. Que 2. - Find the cube root of 830584 -
Last digit is = 4
Ignore the last 3 digits = 830584
Now check the closest cube of remaining digit 830
729 < 830 < 1000
So we will take the cube of 9 which is 729. (Lower cube)
So the answer is
𝟑
𝟖𝟑𝟎𝟓𝟖𝟒 = 𝟗𝟒
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8. Que 3. - Find the cube root of 216000
Last digit is = 0
Ignore the last 3 digits = 216000
Now check the closest cube of remaining digit 216
216 is exact cube of 6
So the answer is
𝟑
𝟐𝟏𝟔𝟎𝟎𝟎 = 𝟔𝟎
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9. Que 4. - Find the cube root of 21952 -
Last digit is = 2
So it will be changed with 8
Ignore the last 3 digits = 21952
Now check the closest cube of remaining digit 21
8 < 21 < 27
So we will take the cube of 2 which is 8 (Lower cube)
So the answer is
𝟑
𝟐𝟏𝟗𝟓𝟐 = 𝟐𝟖
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10. Que 5. - Find the cube root of 636056 -
Last digit is = 6
Ignore the last 3 digits = 636056
Now check the closest cube of remaining digit 636
512 < 636 < 729
So we will take the cube of 8 which is 729. (Lower cube)
So the answer is
𝟑
𝟔𝟑𝟔𝟎𝟓𝟔 = 𝟖𝟔
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11. USEFUL LINKS TO HELP YOU
IBPS PO Recruitment Exam 2016-17
SSC CGL Exam Syllabus
Railway RRB Books for Preparation
IBPS SO Recruitment 2016-17