A number when divided by 108 leaves a remainder of 79. What would be the remainder if the same number is divided by 18?

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Understand the Problem

The question is asking us to find the remainder when a certain number is divided by 18, given that when the same number is divided by 108, the remainder is 79. This is a problem related to number theory and remainders.

Answer

7
Answer for screen readers

7

Steps to Solve

  1. Express the given information as an equation

Let the number be $n$. We are given that when $n$ is divided by 108, the remainder is 79. We can write this as: $n = 108q + 79$, where $q$ is the quotient.

  1. Rewrite the equation to find the remainder when divided by 18

We want to find the remainder when $n$ is divided by 18. Since $108 = 18 \times 6$, we can rewrite the equation as: $n = (18 \times 6)q + 79$.

  1. Isolate the multiples of 18

We can rewrite 79 as a multiple of 18 plus a remainder. Divide 79 by 18: $79 = 18 \times 4 + 7$.

  1. Substitute back into the equation and simplify

Now, substitute this back into the equation for $n$: $n = (18 \times 6)q + (18 \times 4 + 7)$ $n = 18(6q) + 18(4) + 7$ $n = 18(6q + 4) + 7$

  1. Determine the remainder

From the equation $n = 18(6q + 4) + 7$, we can see that when $n$ is divided by 18, the quotient is $6q + 4$ and the remainder is 7.

7

More Information

The remainder when the number is divided by 18 is 7.

Tips

A common mistake is to directly divide 79 by 18 and take the remainder. While this works, it's important to understand the underlying algebraic manipulation that justifies this shortcut.

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