Aptitude - Numbers - Discussion

Discussion Forum : Numbers - General Questions (Q.No. 121)

Numbers

121.

What is the unit digit in the product (3⁶⁵ x 6⁵⁹ x 7⁷¹)?

Answer: Option

Explanation:

Unit digit in 3⁴ = 1 Unit digit in (3⁴)¹⁶ = 1

Unit digit in 3⁶⁵ = Unit digit in [ (3⁴)¹⁶ x 3 ] = (1 x 3) = 3

Unit digit in 6⁵⁹ = 6

Unit digit in 7⁴ Unit digit in (7⁴)¹⁷ is 1.

Unit digit in 7⁷¹ = Unit digit in [(7⁴)¹⁷ x 7³] = (1 x 3) = 3

Required digit = Unit digit in (3 x 6 x 3) = 4.

Discussion:

39 comments Page 4 of 4.

Amar said: 8 years ago

Why we take 3 to the power 4? Please explain.

Prateek said: 9 years ago

Thanks, @Jyoti.

Gayathri said: 9 years ago

Thanks, @Jyothi. It's an easy way.

Soujanya S said: 9 years ago

@Jyothi.

Thanks for explaining it in easy way.

Jenifer said: 9 years ago

Thanks you so much @Jyoti.

Priya said: 9 years ago

I can't understand it. Please anyone explain me clearly.

Jamir said: 8 years ago

Thanks a lot @Jyothi.

Prem said: 8 years ago

Thanks for your clear explanation @Jyothi.

Gjkk said: 1 decade ago

Why we take power of 7 is only 4?

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