Find out the Cube root of 91125

How To find out the value of cube root of 91125

 

We will find all the factors under the cube root of 91125 and then we will take three values at a time and when we apply the cube root on the complete prime factorization then those three values which we have taken at a time then only one value out of three will come out. So let’s start – 

 

Step 1: There are 5 digits in the given number. So here we consider the first two digits from left, i.e., 91 and the last digit 5 from the unit place

 

Step 2: Now we have to find, if the value of a cube is 91. If there is no number found whose value of cube gives the value 91, then we have to consider the cube root number whose cube value is lesser than 91

 

Step 3: The nearest value of cube which is lesser than 91 is 64

4ᶟ= 64

 

Step 4: Now the first digit in the value of cube root of 91125 becomes 4

Let us assume the second digit after 4 be x (= 4x)

 

Step 5: To find the value of ‘x’ in 4x, which is the value of cube root of 91125.

According to the method to find the value of ‘x’ we have to consider the last digit of the cube value, 91125.

Now we know that the cube value of 5 is 125.

(for easy understanding, 5 is the value of cube root of 125.

i.e., when 5 multiplied thrice its value is 125. And in the value 91125 the last digit also is 5. Hence the unit digit is 5, x=5)

So the last digit in the unit place is 5

 

Step 6 : Hence the value of x in ∛91125 = 45 ,value of the last digit in unit place becomes 5

i.e., x= 5

Therefore, we can claim that the value of cube root of the given number 91125 is 45

 

Step 7: The final answer can be expressed as ∛91125 = 45

 

Multiple choice Question –

 

NO.1) What should be the One’s digit in the cube root for the cube number 91125?

a) 5

b) 4

c) 2

d) 6

Answer is a) 5

Now we know that the cube value of 5 is 125.

i.e., when 5 multiplied thrice its value is 125. And in the value 91125 the last digit also is 5. Hence the

unit digit is, x=5

So the last digit in the unit place is 5

 

No.2) How many times 45 is multiplied to get the value 91125 ?

a) Two times

b) Three times

c) Four times

d) Five times

Answer is b) three times

Because 45 multiplied three times gives the value 91125which means 45ᶟ = 91125

Updated: October 19, 2021 — 3:49 pm

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