Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 10)
10.
What is the unit digit in {(6374)1793 x (625)317 x (341491)}?
Answer: Option
Explanation:
Unit digit in (6374)1793 = Unit digit in (4)1793
= Unit digit in [(42)896 x 4]
= Unit digit in (6 x 4) = 4
Unit digit in (625)317 = Unit digit in (5)317 = 5
Unit digit in (341)491 = Unit digit in (1)491 = 1
Required digit = Unit digit in (4 x 5 x 1) = 0.
Discussion:
123 comments Page 11 of 13.
Nilkanta Das said:
6 years ago
Nice explanation, Thanks all.
Shivam rana said:
6 years ago
Thanks @Seema.
Pooja said:
6 years ago
As in 6374 = unit digit is '4'
in 625 = unit digit is '5'
in 341 = unit digit is '1'.
Now just multiply all the digit units =4 * 5 * 1=20
In 20, the unit digit is '0'.
Again,
In the power of 6374 i.e,1793 = unit digit is '3',
In the power of 625 i.e, 317 = unit digit is '7',
In the power of 341 i.e, 491 = unit digit is '1',
Now multiply all the digit units = 3*7*1=21.
In 21, the unit digit is '1'.
Hence,
The required unit digit is, 0^1.
= 0 (answer).
in 625 = unit digit is '5'
in 341 = unit digit is '1'.
Now just multiply all the digit units =4 * 5 * 1=20
In 20, the unit digit is '0'.
Again,
In the power of 6374 i.e,1793 = unit digit is '3',
In the power of 625 i.e, 317 = unit digit is '7',
In the power of 341 i.e, 491 = unit digit is '1',
Now multiply all the digit units = 3*7*1=21.
In 21, the unit digit is '1'.
Hence,
The required unit digit is, 0^1.
= 0 (answer).
(2)
Harry said:
6 years ago
Thanks @Pooja.
Sandeep said:
6 years ago
The easiest way is in 1793 we take last two digits and 4 divide by means 93÷4 the remainder is 1 so in 6374 the unit digit is 4 so 4^1 is 4.
The answer is 4*5*1=20 unit digit is 0.
The answer is 4*5*1=20 unit digit is 0.
Prajna Samal said:
6 years ago
What is short trick of this sum? I can't understand easily.
Sumanth said:
6 years ago
You mentioned method is suitable for all the unit digit problems.
Kanimozhi said:
6 years ago
What is short trick of this sum? I can't understand easily.
Vamsi krishna said:
6 years ago
First, we can add the last unit digits without considering powers.
4+5+1=10.
The above 10 last digits was zero.
4+5+1=10.
The above 10 last digits was zero.
Reza Khan(BD) said:
6 years ago
We know,
(4)^n=unit digit 4; if n=even number.
Cause 4^(1/3/5) = unit digit 4.
So, 4^1793 gives unit digit 4.
(4)^n=unit digit 4; if n=even number.
Cause 4^(1/3/5) = unit digit 4.
So, 4^1793 gives unit digit 4.
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