Aptitude - Numbers - Discussion
Discussion Forum : Numbers - General Questions (Q.No. 90)
90.
What is the unit digit in(795 - 358)?
Answer: Option
Explanation:
Unit digit in 795 = Unit digit in [(74)23 x 73]
= Unit digit in [(Unit digit in(2401))23 x (343)]
= Unit digit in (123 x 343)
= Unit digit in (343)
= 3
Unit digit in 358 = Unit digit in [(34)14 x 32]
= Unit digit in [Unit digit in (81)14 x 32]
= Unit digit in [(1)14 x 32]
= Unit digit in (1 x 9)
= Unit digit in (9)
= 9
Unit digit in (795 - 358) = Unit digit in (343 - 9) = Unit digit in (334) = 4.
So, Option B is the answer.
Discussion:
37 comments Page 2 of 4.
Ranga said:
7 years ago
Because 6 is an actual difference but negative come to take 10 value.
i.e means 10-6 = 4 is the right answer.
i.e means 10-6 = 4 is the right answer.
(1)
J GOPINATH said:
9 years ago
Here as per the logic, it's if subtracted it will be 6 but with the negative symbol so you have borrow 10 from the previous place i. e, ten's place which makes the 3 to be 13 and hence 13-9=4 which the correct answer choice.
(1)
Jot said:
1 decade ago
My answer is 6. But how is it 4? Please elaborate clearly.
(1)
Kala said:
1 decade ago
7^3=343 and 3^2=9
difference 343-9
ans 4
How? Please explain every step.
difference 343-9
ans 4
How? Please explain every step.
(1)
Shahid said:
1 decade ago
EVERYTHING THAT I EXPLAINED WAS RIGHT ..BUT I UN NOTICINGLY DIVIDED 95/4 whose remainder is 3
and 58/4 remainder is 2
so 7^3=343 and 3^2=9
and the difference is 343-9 where there 334.
So 4 is the answer.
and 58/4 remainder is 2
so 7^3=343 and 3^2=9
and the difference is 343-9 where there 334.
So 4 is the answer.
(1)
Jangyaseni Mohanty said:
10 months ago
Agree, the answer is 4.
Ravi said:
2 decades ago
How do define unitdigit. Explain?
Revanth said:
2 months ago
It's simple.
Just take the power cycle of 7 & 3.
A power cycle of 7 gives (7^4=1).
And power cycle of 3 gives (3^4 =1).
Apply the Divisibility rule of 4 (if the last 2 digits of a number are divided by 4 then the whole number is divided by 4).
Here:
7^95 - 3^58 =?
7^95 = (7^4) *7^ (95/4) = 1*7^3=343.
3^58 = (3^4) *3^ (58/4) = 1*3^2=9.
343-9= 334.
Units Digit value is 4.
Just take the power cycle of 7 & 3.
A power cycle of 7 gives (7^4=1).
And power cycle of 3 gives (3^4 =1).
Apply the Divisibility rule of 4 (if the last 2 digits of a number are divided by 4 then the whole number is divided by 4).
Here:
7^95 - 3^58 =?
7^95 = (7^4) *7^ (95/4) = 1*7^3=343.
3^58 = (3^4) *3^ (58/4) = 1*3^2=9.
343-9= 334.
Units Digit value is 4.
Premnath said:
7 years ago
How come we take,
7^95 = 7^92+7^3?
What happens if we take, 7^95 = 7^93 + 7^2, How to solve this? Please tell me.
7^95 = 7^92+7^3?
What happens if we take, 7^95 = 7^93 + 7^2, How to solve this? Please tell me.
Snehasish said:
7 years ago
To all values of n = (x*m-a*m) is divisible by (x- a) thus 7-3 = 4 is the Ans.
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