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3 votes
A number that divided by 3 leaves 2, divided by 5 leaves 3 and divided by 7 leaves 2. What is the number?

2 Answers

5 votes

Final answer:

The question involves finding a number that satisfies a system of congruences, which can be solved using the Chinese Remainder Theorem. The conditions are that the number leaves specific remainders when divided by 3, 5, and 7.

Step-by-step explanation:

The student is looking for a number that fulfills three different modular conditions: it leaves a remainder of 2 when divided by 3, a remainder of 3 when divided by 5, and a remainder of 2 when divided by 7. This kind of problem is commonly solved using the Chinese Remainder Theorem, which is a method for solving systems of simultaneous congruences with different moduli.

To find such a number, we'd need to solve the system of congruences:

  • x ≡ 2 (mod 3)
  • x ≡ 3 (mod 5)
  • x ≡ 2 (mod 7)

Without providing the detailed calculation here, which involves finding a common solution to these congruences, we can say that the smallest positive integer that satisfies all these conditions would be the answer to this problem.

User Denis Fuenzalida
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8.0k points
4 votes
x/3=2
x=6

x/5=3
x=15

x/7=2
x=14

Each time, you multiply both sides by the denominator.

Hope this helps :)
User August Flanagan
by
8.1k points