# What does a ≡ b (mod n) mean? Basic Modular Arithmetic, Congruence | Summary and Q&A

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April 23, 2018
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What does a ≡ b (mod n) mean? Basic Modular Arithmetic, Congruence

## TL;DR

Congruence modulo N means that two numbers have the same remainder when divided by N.

## Key Insights

• 🙅 Congruence modulo N implies that two numbers have the same remainder when divided by N.
• 🎛️ The equation form a = kn + b is a useful alternative interpretation of congruence modulo N.
• #️⃣ Subtracting the two numbers in a congruence equation gives a multiple of N.
• 🎛️ The equation form a - b = kn indicates that N divides into the difference between the two numbers.
• 🪜 Negative remainders can be resolved by adding the modulus to obtain a positive remainder.
• 🙅 Congruence modulo N is a fundamental concept in number theory and modular arithmetic.
• ❓ Congruence can be used to solve equations and proofs in mathematics.

## Transcript

like what does this mean when we have a is congruent to b mod n and all the following are pretty much equivalent and depending on the situations you can interpret them differently okay so perhaps the first thing i want to tell you guys that when we have a is congruent to b mod n this means that a and b have the same remainder and i will put on quot... Read More

### Q: What does "a is congruent to b mod n" mean?

"a is congruent to b mod n" means that a and b have the same remainder when divided by n.

### Q: Can congruence with negative numbers be interpreted differently?

Yes, congruence with negative numbers can be handled by adding the modulus to obtain a positive remainder.

### Q: How can congruence be written in equation form?

Congruence can be written as a = kn + b, where k is a constant and b represents the remainder.

### Q: How can congruence be used to solve equations?

By converting congruence into an equation, it becomes easier to solve for unknown variables in the equation.

## Summary & Key Takeaways

• Congruence modulo N means that two numbers have the same remainder when divided by N.

• An equation form, a = kn + b, can also be used to interpret congruence modulo N.

• Congruence can be used to solve equations and proofs in mathematics.