Illustrative Mathematics Grade 4, Unit 4: From Hundredths to Hundreds of Thousands
In this unit, your child works with place value in both directions, from hundredths up to hundreds of thousands. They write fractions as decimals and compare them, and read, compare, and round whole numbers up to a million. Building on last unit's fractions, this sets up multiplicative comparison and measurement next.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 4?
- Seeing that each place is ten times the place to its right, from hundredths and tenths up to hundred thousands. Learn more: Why each place is worth ten times the next
- Reading, writing, and comparing numbers up to 1,000,000, and placing them on a number line. Learn more about reading and writing numbers up to a million: Reading and writing numbers up to a million · Learn more about comparing numbers up to a million
- Rounding large numbers to the nearest ten thousand or hundred thousand, and deciding which place makes sense for an estimate. Learn more: Rounding big numbers to any place
- Renaming tenths as hundredths to add amounts like 3/10 + 9/100 = 39/100. Learn more: Adding tenths and hundredths together
- Writing decimals for fractions with 10 or 100 in the denominator, and locating them on number lines. Learn more: Writing fractions as decimals, like 0.62
- Comparing decimals to the hundredths, like 0.09 and 0.1, and explaining with grids, number lines, and place value. Learn more: Comparing decimals like 0.09 and 0.1
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
Compare 40 thousands and 4 ten thousands. Which is true?
- 4 ten thousands is more
- They are equal
- 40 thousands is more
How you can help
- Ask how many pennies, dimes, and dollars make $10. Talk about why each coin or bill is worth ten times the one before: 1,000 pennies, 100 dimes, and 10 dollars.
- Read a big number from a map or the news, like 263,804. Ask your child to round it to the nearest ten thousand and hundred thousand, then decide which is more useful.
- Compare two race times, like 12.45 seconds and 12.5 seconds. Ask your child which is faster and to explain with hundredths.
Where kids can get stuck
- Writing 3/100 as 0.3, which makes the number ten times too large.
- Comparing 0.25 and 0.3 as if they were 25 and 3.
- Dropping digits when rounding, so 263,804 to the nearest ten thousand becomes 263,000.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- place value
- The value a digit has because of its place in a number.
- digit
- Any of the symbols 0 through 9 used to write numbers.
- round
- To change a number to a nearby, easier number, like 6,812 to 7,000.
- tenth
- One of 10 equal parts of a whole, written 1/10 or 0.1.
- hundredth
- One of 100 equal parts of a whole, written 1/100 or 0.01.
- decimal
- A number written with a decimal point, like 0.62, to show parts of a whole.
- decimal point
- The dot that separates the whole number from the tenths and hundredths.
- hundredths place
- The second place to the right of the decimal point.
Want to help your child master place value and decimals?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
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Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does Illustrative Mathematics Grade 4 Unit 4 cover?
Illustrative Mathematics Grade 4 Unit 4 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 4.NBT.A.1: Know that each place is worth 10 times the place to its right.
- 4.NBT.A.2: Read, write, and compare numbers up to a million.
- 4.NBT.A.3: Round large numbers to any place, like 6,812 to 7,000.
- 4.NF.C.5: Turn tenths into hundredths to add them, like 3/10 + 4/100.
- 4.NF.C.6: Write tenths and hundredths as decimals, like 4/10 = 0.4.
- 4.NF.C.7: Compare decimals to hundredths, like 0.09 and 0.1.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.