Solve Decimal Division: 0.9 ÷ (-0.15) Step-by-Step

Decimal Division with Negative Numbers

Solve the following expression:

(+0.9):(0.15)= (+0.9):(-0.15)=

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:08 Let's solve the problem together.
00:12 Remember, when you divide a positive number by a negative number, the result is always negative.
00:23 First, change decimal numbers into fractions for easier manipulation.
00:28 Next, rewrite division as multiplication using a reciprocal. This means flipping the fraction.
00:36 Switch the numerator and the denominator in the fraction.
00:40 Now, let's simplify everything we can. This is called reducing the fractions.
00:46 Remember to multiply the numerators together and multiply the denominators together.
00:55 For example, factor 90 into 3 times 30.
00:59 Keep reducing as much as possible until you cannot simplify anymore.
01:04 And that's how we find the solution to this question. Great job!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following expression:

(+0.9):(0.15)= (+0.9):(-0.15)=

2

Step-by-step solution

Since we are dividing a positive number by a negative number, the result must be a negative number:

+:= +:-=-

First, let's convert the numbers in the exercise to simple fractions:

0.9=910 0.9=-\frac{9}{10}

0.15=15100 0.15=\frac{15}{100}

Resulting in the following exercise:

(910:15100)= -(\frac{9}{10}:\frac{15}{100})=

Let's convert the division to multiplication, don't forget to switch between numerator and denominator:

(910×10015)= -(\frac{9}{10}\times\frac{100}{15})=

Let's reduce by 10 and obtain the following:

(9×1015)= -(9\times\frac{10}{15})=

Let's combine into one exercise:

(9×1015)=9015 -(\frac{9\times10}{15})=-\frac{90}{15}

Let's break down 90 into a multiplication exercise:

3×3015= -\frac{3\times30}{15}=

Let's reduce the numerator and denominator by 15 and obtain:

3×2=6 -3\times2=-6

3

Final Answer

6 -6

Key Points to Remember

Essential concepts to master this topic
  • Rule: Positive divided by negative equals negative result
  • Technique: Convert to fractions: 0.9 = 9/10, 0.15 = 15/100
  • Check: Verify -6 × (-0.15) = 0.9 ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting the negative sign in the final answer
    Don't ignore sign rules and write 6 instead of -6! When dividing positive by negative, the result must be negative. Always apply the sign rule: positive ÷ negative = negative.

Practice Quiz

Test your knowledge with interactive questions

What will be the sign of the result of the next exercise?

\( (-2)\cdot(-4)= \)

FAQ

Everything you need to know about this question

Why is the answer negative when I'm dividing decimals?

+

The sign rule applies to all division, including decimals! Since we're dividing a positive number (0.9) by a negative number (-0.15), the result must be negative.

Do I have to convert decimals to fractions?

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Not always! Converting to fractions like 910÷15100 \frac{9}{10} ÷ \frac{15}{100} can make the division clearer, but you can also divide decimals directly: 0.9 ÷ 0.15 = 6, then apply the negative sign.

How do I remember the sign rules for division?

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Use this simple pattern: Same signs = Positive, Different signs = Negative. Since we have (+) ÷ (-), the signs are different, so the answer is negative.

Can I check my answer without doing the whole problem over?

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Yes! Multiply your answer by the divisor: 6×(0.15)=0.9 -6 × (-0.15) = 0.9 . If you get the original dividend, your answer is correct!

What if I get confused with all the fraction steps?

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Try the direct method first: divide 0.9 by 0.15 to get 6, then apply the sign rule to get -6. The fraction method is just another way to show the same work!

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