Converting decimals to fractions example 1 | Decimals | Pre-Algebra | Khan Academy

We're practicing how to convert a lonely decimal into a happy fraction.

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0.15를 분수로
표현해 봅시다

먼저 각 숫자의 자릿값을
잘 파악해야 합니다

1은 소수 첫째 자리에 있으므로
1 × 1/10로 생각할 수 있고

5는 소수 둘째 자리에 있으므로

5 × 1/100입니다

두 수의 합으로
다시 써 볼게요

1은 1/10이고

5는 5/100이므로

1/10 + 5/100

두 분수를 더하려면
공통분모를 찾아야 합니다

공통분모는 100이에요

10과 100의 최소공배수가
100이기 때문이죠

그러면 두 수의 분모는
100이 될 거예요

5/100는 그대로
5/100입니다

1/10의 분모에는
10을 곱했으므로

분자에도 10을 곱하면
10/100이 됩니다

이제 더해 봅시다
10 + 5 = 15

따라서 15/100이 됩니다

암산으로 더 빨리
풀 수도 있어요

가장 작은 자릿수가
백분의 일의 자리이니까

이것을 1/10 대신
10/100으로 보거나

15/100이라고 보면
훨씬 간단하겠죠

이제 분수를
약분해 볼게요

분자와 분모를
5로 나누면

분자는 15 ÷ 5 = 3
분모는 100 ÷ 5 = 20

따라서 약분하면
답은 3/20입니다