Learn with Amar
Teaching video
A teaching recording for this chapter has not been published yet. Start with the worked example below and explore the related animations where available.
Grade 4 chapters and video availability01 · Read and understand
What you will learn
- Align decimal places when adding two-place decimals.
- Explain your method and check what the result means in the stated situation.
Before you start
Multiplication and division facts, simple fractions, place value, and basic length and area measurement.
Keep paper nearby. Read the question once for the context, then again to identify what is known and what you need to find.
Start with a question
A pretend notebook costs $2.35 and a pencil costs $0.80. What total?
Why this math matters
Use whole cents to check decimal addition in a simple price example. The worked example shows how to connect the situation, its mathematical representation, and a check on the result.
Set up the model
A useful answer starts with clear assumptions:
- Use the units, grouping rules, and reference whole stated in the question.
- Treat the supplied counts and measurements as exact within the classroom model, unless an estimate or a random outcome is requested.
02 · Work through the example
Follow the reasoning, one step at a time.
Try to predict the next step before reading it. After each calculation, explain why the operation makes sense and how it helps answer the original question.
Work through it with Amar
See this example unfold.
The complete worked example, one idea at a time.
Add tenths and hundredths together
PausedQuestion: Start with the question. Paused.
Question
Start with the question
A pretend notebook costs $2.35 and a pencil costs $0.80. What total?
Before you calculate
Read what is known and what you need to find. Make a prediction before moving to the first calculation.
Starts paused. Play advances through the full text at a reading pace; pause whenever you need more time. Previous, Next, and the phase buttons let you set your own pace. Playback pauses when this walkthrough leaves the screen or you switch tabs.
Your device’s reduced-motion setting keeps each phase still. Manual controls remain available. The full written solution stays below.
Represent the situation
2.35 + 0.80
Align dollar, tenth-dollar, and hundredth-dollar places.
Connect the parts
35 cents + 80 cents = 115 cents
Exchange one hundred cents for one dollar.
State and check the result
Total = $3.15
Two dollars plus one dollar fifteen cents gives three dollars fifteen.
The result
Total = $3.15
Two dollars plus one dollar fifteen cents gives three dollars fifteen.
Common mistakes to catch
- Align decimal points, not the final digit of each number.
- Add quantities with matching units.
03 · Practice independently
Try it before revealing the answer.
Use paper or a calculator as needed. Write your units and reasoning, then open the hint or explanation to check your approach.
Practice 1
Find 1.4 + 0.27.
Show a hint
Rename 1.4 as 1.40.
Reveal answer and explanation
1.67
Forty hundredths plus twenty-seven hundredths is sixty-seven hundredths.
Practice 2
Why is 0.3 + 0.04 not 0.7?
Show a hint
Three tenths equals thirty hundredths.
Reveal answer and explanation
The correct sum is 0.34
Thirty hundredths plus four hundredths is thirty-four hundredths.
Take the idea with you
Use whole cents to check decimal addition in a simple price example.
04 · Reflect and continue
Can you explain it in your own words?
Before moving on, explain the main idea without looking at the worked example. Try both practice questions, check your reasoning, and name one mistake you now know how to avoid. Return to a step if you still need support.
Up next: Read decimals between labeled marks
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