Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GRE score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
Your score will improve and your results will be more realistic
Is there something wrong with our timer?Let us know!
I have posted a video on YouTube to discuss Units' Digit of Power of 8
Attached pdf of this Article as SPOILER at the top! Happy learning!
Following is Covered in the Video
Theory of Units' Digit of Power of 8
⁍ Find Units’ digit of 891 ? ⁍ Find Units’ digit of 857 ? ⁍ Find Units’ digit of 888 ? ⁍ Find Units’ digit of 840a+41 (given that a is a positive integer)? ⁍ Find Units’ digit of 17578979 ?
Theory of Units' Digit of Power of 8
• To find units' digit of any positive integer power of 8
We need to find the cycle of units' digit of power of 8
81 units’ digit is 8 82 units’ digit is 4 83 units’ digit is 2 84 units’ digit is 6
85 units’ digit is 8 86 units’ digit is 4 87 units’ digit is 2 88 units’ digit is 6
=> The power repeats after every 4th power => Cycle of units' digit of power of 8 = 4 => We need to divide the power by 4 and check the remainder => Units' digit will be same as Units' digit of 8Remainder
NOTE: If Remainder is 0 then units' digit = units' digit of 8Cycle = units' digit of 84 = 1
Sol: Units' digit of power of any number = Units' digit of power of the units' digit of that number => Units’ digit of 17588979 = Units’ digit of 88979 => Remainder of 8979 divided by 4 = Remainder of last two digits by 4
How to Solve: Units' Digit of Power of 8
[#permalink]
26 Aug 2024, 20:30
1
Thank you for reading the post and sharing the comment.
dipenshome wrote:
For Q3, I think the answer provided is wrong. If Remainder is 0 then units' digit will be 6, not 1. Unit Digit of 84=6
You are correct, there was a typo. Unit's digit of 84 = 6 as mentioned in the pattern in the post above. Post has been corrected to reflect the same. Thank you.
dipenshome wrote:
The answer for Q5 doesn't make any sense.
Yes, the question is 1758^8979 Post has been corrected to reflect the same. Thank you.
gmatclubot
How to Solve: Units' Digit of Power of 8 [#permalink]
22 Dec 2023, 04:46 
