[IntroNumTheory] Determining the remainder by using congruence

  • Thread starter Leo Liu
  • Start date
  • Tags
    Remainder
In summary, the conversation discusses a strategy for using congruence to solve a question involving powers. The person proposes to simplify the congruence and then apply the Congruence to remainder method. They demonstrate this by showing that ##453^{234}\equiv 3^{234} (mod\, 100)##, but they are unsure how to proceed further. Another person suggests using a calculator or spreadsheet to find a low modulo 100 value for powers of 3.
  • #1
Leo Liu
353
156
Homework Statement
.
Relevant Equations
.
https://www.physicsforums.com/attachments/292386

I need to use the congruence to solve this question. My strategy is to write the question as a congruence and then simplify the congruence so that I can apply Congruence to remainder to get the remainder. My work is as follows:
We know that
##453\equiv 53 (mod\, 100)##
Thus,
##453^{234}\equiv 53^{234} (mod\, 100)## by Congruence Power.
Also since
##53^2\equiv 9 (mod\, 100)##,
##53^234\equiv 9^{117} (mod\, 100)##.
So by the transitivity property, we have
##453^{234}\equiv 3^{234} (mod\, 100)##
But I am stuck here. Can someone help me out, please?
 
Physics news on Phys.org
  • #2
Why not do powers of 3 on a calculator (or better on a spreadsheet) until something low modulo 100 appears?
 
  • Like
Likes Leo Liu

FAQ: [IntroNumTheory] Determining the remainder by using congruence

What is the basic concept of congruence in number theory?

Congruence in number theory refers to the idea that two numbers have the same remainder when divided by a given number. In other words, if two numbers have the same remainder when divided by a certain number, they are considered congruent.

How is congruence used to determine the remainder in number theory?

Congruence is used to determine the remainder by finding the remainder of a number when divided by a given modulus (or divisor). This is done by using the formula a ≡ b (mod m), where a is the number being divided, b is the remainder, and m is the modulus. The remainder b can then be determined by solving for it in the congruence equation.

Can congruence be used for any type of number?

Yes, congruence can be used for any type of number, including integers, fractions, and even complex numbers. As long as the numbers have the same remainder when divided by a given modulus, they are considered congruent.

What is the significance of determining the remainder using congruence?

Determining the remainder using congruence is important in number theory because it allows for simplification and easier calculations. It also helps in solving problems related to divisibility and finding patterns in numbers.

Are there any limitations to using congruence to determine the remainder?

One limitation of using congruence is that it only applies to numbers that are relatively prime (i.e. they have no common factors other than 1). Additionally, it may not always provide the most efficient method for finding the remainder, as it requires solving an equation for the remainder instead of simply dividing the numbers.

Back
Top