Question

Find the unit digit of the cube of the following: 1) 26781 2) 2352 3) 2389 4) 3666

Answer 1

Answer:

$1)26781 = 61 \times 61 \times 61 = 61 ^{3}$

$2)2352 = (13.3)^{3}$

$3)2389 = (13.37)^{3}$

$4)3666 = (15.42)^{3}$

Answer 2

Given : The given numbers are 26781, 2352, 2389 and 3666

To find : The unit digit of the cubes of the given numbers.

Solution :

We can simply solve this mathematical problem by using the following mathematical process. (our goal is to determine the unit digits of the cubes of the given numbers)

For this, we need to take the unit digits of the given numbers. And, then we need to calculate the cubes of those unit digits only. The digits which will be at the unit place of those cubes will be the unit digits which will be at the unit place of the cube of the entire number.

So, for 26781 :

• Unit digit = 1
• Unit digit's cube = (1)³ = 1
• The digit at the cube's unit place = 1
• So, (26781)³ has 1 as its unit digit.

So, for 2352 :

• Unit digit = 2
• Unit digit's cube = (2)³ = 8
• The digit at the cube's unit place = 8
• So, (2352)³ has 8 as its unit digit.

So, for 2389 :

• Unit digit = 9
• Unit digit's cube = (9)³ = 729
• The digit at the cube's unit place = 9
• So, (2389)³ has 9 as its unit digit.

So, for 3666 :

• Unit digit = 6
• Unit digit's cube = (6)³ = 216
• The digit at the cube's unit place= 6
• So, (3666)³ has 6 as its unit digit.

Hence, the unit digits of the cube of 26781, 2352, 2389 and 3666 are 1, 8 , 9 and 6 respectively.