(a) Start by squaring both sides of the congruence 34 = 81 (mod 100) to prove that 38 = 61 (mod 100) and then prove that 3¹6 = 21 (mod 100). What does this tell you about the last two digits in the decimal repre- sentation of 316? (b) Use the two congruences in Part (24a) and laws of exponents to deter- mine r where 320 = r (mod 100) and r € Z with 0 < r < 100. What does this tell you about the last two digits in the decimal representation of 320? 158 @080 BY NC SA Chapter 3. Constructing and Writing Proofs in Mathematics (c) Determine the last two digits in the decimal representation of 3400 (d) Determine the last two digits in the decimal representation of 4804. Hint: One way is to determine the "mod 100 values” for 4², 44, 48, 416, 432, 464, and so on. Then use these values and laws of exponents to determine r, where 4804 = r (mod 100) and r € Z with 0 < r < 100. (e) Determine the last two digits in the decimal representation of 33356 (f) Determine the last two digits in the decimal representation of 7403

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Question
100%
The Last Two Digits of a Large Integer.
Notice that 7, 381, 272 = 72 (mod 100) since 7, 381, 272-72= 7, 381, 200,
which is divisible by 100. In general, if we start with an integer whose deci-
mal representation has more than two digits and subtract the integer formed
by the last two digits, the result will be an integer whose last two digits are
00. This result will be divisible by 100. Hence, any integer with more than
2 digits is congruent modulo 100 to the integer formed by its last two digits.
(a) Start by squaring both sides of the congruence 34 = 81 (mod 100) to
prove that 38 = 61 (mod 100) and then prove that 3¹6 = 21 (mod 100).
What does this tell you about the last two digits in the decimal repre-
sentation of 316?
(b) Use the two congruences in Part (24a) and laws of exponents to deter-
mine r where 320 = r (mod 100) and r € Z with 0 <r < 100. What
does this tell you about the last two digits in the decimal representation
of 320?
158
C030
BY NO SA
Chapter 3. Constructing and Writing Proofs in Mathematics
(c) Determine the last two digits in the decimal representation of 3400
(d) Determine the last two digits in the decimal representation of 4804
Hint: One way is to determine the "mod 100 values" for 42, 44, 48,
416, 432, 464, and so on. Then use these values and laws of exponents
to determine r, where 4804 = r (mod 100) and r € Z with 0 < r <
100.
(e) Determine the last two digits in the decimal representation of 33356
(f) Determine the last two digits in the decimal representation of 7403
Transcribed Image Text:The Last Two Digits of a Large Integer. Notice that 7, 381, 272 = 72 (mod 100) since 7, 381, 272-72= 7, 381, 200, which is divisible by 100. In general, if we start with an integer whose deci- mal representation has more than two digits and subtract the integer formed by the last two digits, the result will be an integer whose last two digits are 00. This result will be divisible by 100. Hence, any integer with more than 2 digits is congruent modulo 100 to the integer formed by its last two digits. (a) Start by squaring both sides of the congruence 34 = 81 (mod 100) to prove that 38 = 61 (mod 100) and then prove that 3¹6 = 21 (mod 100). What does this tell you about the last two digits in the decimal repre- sentation of 316? (b) Use the two congruences in Part (24a) and laws of exponents to deter- mine r where 320 = r (mod 100) and r € Z with 0 <r < 100. What does this tell you about the last two digits in the decimal representation of 320? 158 C030 BY NO SA Chapter 3. Constructing and Writing Proofs in Mathematics (c) Determine the last two digits in the decimal representation of 3400 (d) Determine the last two digits in the decimal representation of 4804 Hint: One way is to determine the "mod 100 values" for 42, 44, 48, 416, 432, 464, and so on. Then use these values and laws of exponents to determine r, where 4804 = r (mod 100) and r € Z with 0 < r < 100. (e) Determine the last two digits in the decimal representation of 33356 (f) Determine the last two digits in the decimal representation of 7403
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps with 3 images

Blurred answer
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,