Don’t be surprised if you’ve never used a number line to divide, just learn how to explain it to your kids. Homework Unlocked is here to help you do it. Homework Unlocked offers homework help to parents so you can help your kids excel in math. Here, Homework Unlocked explains dividing decimals using a number line.
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Dividing Decimals Using a Number Line
Number lines can be an excellent way for your kids to visualize math problems. They can help with addition and subtraction, and multiplication and division.
Here, we will show you step by step how to use a number line to solve for problems involving decimals and division by following three steps:
- Rewrite the expression.
- Fill in the missing intervals on the number line.
- Use the completed number line to solve!
When asked to solve a division problem using a number line your kids will almost always be given a partially filled in number line to work with, so let’s start by using one as an example.
Example 1. Divide 0.9 by 0.3 using the number line below
Step 1: Rewrite the expression
When the problem states a number ‘a’ is being divided by a number ‘b’ it’s really asking how many ‘b’s’ can fit into number ‘a’. Therefore, another way of writing 0.9 ÷ 0.3 that might make more sense to your child is,
How many 0.3s are in 0.9?
Step 2. Fill in all the intervals of our number line:
Since we are trying to answer the question, “how many 0.3s are in 0.9,” our number line interval in this example is 0.3. Instruct your child to fill in each blank on our number line by adding 0.3 to the number to the left of the blank. Since we are adding, move from left to right.
Looking at the number line, we see that our first number is 0.
0 + 0.3 = 0.3, now we can fill in our fist blank with 0.3.
Now let’s move one step to the right to the next blank.
0.3 + 0.3 = 0.6, now we can fill in our second blank with 0.6.
Before we move on, it’s helpful to remind your child to check his or her work by adding another interval. If we did this correctly our second blank (0.6) plus our interval (0.3) will equal 0.9.
0.6 + 0.3 = 0.9 Great!
Step 3 Solve:
At this point, go back through the original problem with your child. Ask him or her the following:
- Question: What was our original question? Answer: When asks to divide 0.9 by 0.3 we are really asking How many 0.3s are in 0.9?
- Question: How did we find the interval? Answer: Since we’re asking how many 0.3’s fit in 0.9, 0.3 (our divisor) must be our interval.
Now we can simply count how many intervals are in our number line to answer this question.
Counting from left to right we see that it takes 3 intervals of 0.3 to get from 0 to 0.9. Therefore, there are 3, 0.3s in 0.9.
Finally, we need to solve for 0.9 ÷ 0.3.
0.9 ÷ 0.3 = number of intervals = 3
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