Home




Number Theory

Categories : Number Theory

Number Theory GMATWhat is the ten’s digit of 7^195?

A) 3
B) 4
C) 5
D) 6
E) 7

Solution

This question is based on the cyclicity concept in number theory.

Ten’s digit of powers of 7 follows a cyclic pattern as depicted:

7^1 = 07                7^5 = 16807

7^2 = 49                7^6 = 117649

7^3 = 343                7^7 = 823543

7^4 = 2401                7^8 = 5764801

Every fourth power of 7 has its ten’s place repeated.

Now, let’s break 195 (power of 7) into multiple of 4

195 = 48 * 4 + 3

The 7^195 will have its tens digit the same as 7^3 has, i.e. 4

Correct Answer: B

About the Author

...




Navigate F1GMAT


F1GMAT Services (MBA Applicants) 


F1GMAT's Books

MBA Salary(Latest Salary Data)
 
MBA Admission Interview Tips

Funding 

Deadlines

MBA Application Essays


MBA Recommendation Letter

GMAT Tutorials

GMAT Question Bank

Top MBA Programs

Get F1GMAT's Newsletters (Best in the Industry)
Included in the Newsletter:

  • Ranking Analysis
  • Post-MBA Salary Trends
  • Post-MBA Job Function & Industry Analysis
  • Post-MBA City Review
  • MBA Application Essay Tips
  • School Specific Essay Tips
  • GMAT Preparation Tips
  • MBA Admission Interview Tips
  • School Specific Interview Tips
  • Funding Guidance and
  • Special Consultation Service (only for Subscribers)

Subscribe to F1GMAT's Newsletter