Rounding to the Nearest Hundred

When we round to the nearest hundred, the numbers “residing” in the red areas (up to 850) on the number line are rounded to 800. The numbers in the blue areas are rounded to 900.

Again, distance matters. Numbers from 801 to 849 are closer to 800 than to 900.
Numbers from 851 to 899 are closer to 900 than to 800. And the “middle guy,” 850, is rounded up to 900: 850 ≈ 900.

1. Mark the numbers as dots on the number line (approximately) and round them to either 800 or 900.

804 ≈ ____________

859 ≈ ____________

825 ≈ ___________

850 ≈ ___________

860 ≈ ___________

847 ≈ ___________

808 ≈ ___________

892 ≈ ___________

When rounding to the nearest hundred, look at the TENS DIGIT of the number.

If that digit is 0, 1, 2, 3, or 4, you will round down to the previous hundred.
If that digit is 5, 6, 7, 8, or 9, you will round up to the next hundred.

728 ≈ ? The tens digit is 2, so round down:

728 ≈ 700

471 ≈ ? The tens digitis 7, so round up:

471 ≈ 500

956 ≈ ? The tens digit is 5, so round up:

956 ≈ 1000

2. Round these numbers to the nearest hundred.

416 ≈ ___________

837 ≈ ____________

529 ≈ ___________

960 ≈ ___________

670 ≈ ___________

557 ≈ ___________

254 ≈ ___________

147 ≈ ___________

Things work similarly on this number line when rounding to the nearest hundred:

Numbers up to 2,450 (the middle number) are rounded down to 2,400.
Numbers after 2,450 are rounded up to 2,500.
And the middle guy, 2,450, is rounded up.

3. Round these numbers to 2,400 or to 2,500. You can use the number line above to help you.

a. 2,412 ≈ __________	b. 2,429 ≈ __________
c. 2,478 ≈ ___________	d. 2,490 ≈ ___________

Rounding rules

When rounding to the nearest hundred, look at the TENS DIGIT of the number.

If the tens digit is 0, 1, 2, 3, or 4, you will round down to the previous hundred.

728 ≈ ? The tens digit is 2, so round down:

728 ≈ 700

Notice: the hundreds digit does not change.

If that digit is 5, 6, 7, 8, or 9, you will round up to the next hundred.

471 ≈ ? The tens digit is 7, so round up:

471 ≈ 500

Notice: the hundreds digit increases by one, from 4 to 5.

Whether you round up or down, the tens and ones digits change to zeros.

4. Round these numbers to the nearest hundred.

a. 6,216 ≈ _________	b. 5,923 ≈ _________
c. 1,670 ≈ _________	d. 8,254 ≈ _________
e. 8,019 ≈ _________	f. 2,157 ≈ _________
g. 1,772 ≈ _________	h. 6,849 ≈ _________
i. 801 ≈ _________	j. 255 ≈ _________
k. 9,562 ≈ _________	l. 3,501 ≈ _________

Note especially! 4,952 ≈ ?

Now the tens digit is 5, so we round up. The hundreds digit (9) increases by one (to ten hundreds). But we can't change 9 to 10 or we would get 41052!

Instead, those ten hundreds make a new thousand, so the thousands digit is incremented by one. It is as if '49' changes to '50'. So, we get 4,952 ≈ 5,000

5. Round these numbers to the nearest hundred.

a. 6,986 ≈ _________	b. 5,973 ≈ _________
c. 1,981 ≈ _________	d. 4,945 ≈ _________
e. 2,932 ≈ _________	f. 9,969 ≈ _________
g. 966 ≈ _________	h. 9,982 ≈ _________
i. 798 ≈ _________

6. Round these numbers to the nearest hundred.
Place each answer in the cross-number puzzle.

Across:

a. 2,264 ≈ _______

b. 4,973 ≈ _______

c. 4,248 ≈ _______

d. 545 ≈ _______

Down:

e. 3,709 ≈ _______

f. 672 ≈ _______

g. 5,370 ≈ _______

h. 8,816 ≈ _______

a.	e.

b.
			h.
f.		g.
		c.

	d.

7. Fill in, using rounded numbers.

a. Usually, Mary receives about __________ spam emails daily, but on 5/9 she got about ___________ spams.

b. During the work week from 5/7 till 5/11 she received about __________ spams.

Spam Emails Mary Received
Date	Spams	round to nearest 100
Mo 5/7	125
Tu 5/8	97
Wd 5/9	316
Th 5/10	118
Fr 5/11	106

Place Value Grade 1 Using a 100-bead abacus in elementary math Teaching tens and ones Practicing with two-digit numbers Counting in groups of ten Skip-counting practice (0-100) Comparing 2-digit numbers Cents and dimes Grade 2 Three-digit numbers Comparing 3-digit numbers Grade 3 Place value with thousands Comparing 4-digit numbers Rounding & estimating Rounding to the nearest 100 Grade 4 Place value - big numbers	Add & subtract lessons Grade 1 Missing addend concept (0-10) Addition facts when the sum is 6 Addition & subtraction connection Grade 2 Fact families & basic addition/subtraction facts Sums that go over over the next ten Add/subtract whole tens (0-100) Add a 2-digit number and a single-digit number mentally Add 2-digit numbers mentally Regrouping in addition Regrouping twice in addition Regrouping or borrowing in subtraction Grade 3 Mental subtraction strategies Rounding & estimating	Multiplication Grade 3 Multiplication concept as repeated addition Multiplication on number line Commutative Multiply by zero Word problems Order of operations Structured drill for multiplication tables Drilling tables of 2, 3, 5, or 10 Drilling tables of 4, 11, 9 Grade 4 Multiplying by whole tens & hundreds Distributive property Partial products - the easy way Partial products - video lesson Multiplication algorithm Multiplication Algorithm — Two-Digit Multiplier Scales problems - video lesson Estimation when multiplying
Division Grade 3 Division as making groups Division/multiplication connection Division is repeated subtraction Zero in division Division that is not exact (remainder) Divisibility Grade 4 How to teach long division Long division as repeated subtraction Why long division works Zero in dividend Remainder & long division Two-digit divisor Review of division topics Divisibility Divisibility within 0-1000 Divisibility rules Prime factorization 1 Prime factorization 2 Sieve of Eratosthenes	Fraction Lessons Understanding fractions Finding fractional parts with division Mixed numbers Fractions to mixed numbers and vv. Adding like fractions Equivalent fractions Adding unlike fractions 1 Adding unlike fractions 2: Finding the common denominator Adding mixed numbers Subtracting mixed numbers Subtracting mixed numbers 2 Measuring in inches Comparing fractions Simplifying fractions Multiply fractions by whole numbers Multiply fractions by fractions Multiplication and area Simplify before multiplying Dividing fractions by whole numbers Dividing fractions: fitting the divisor Dividing fractions: reciprocal numbers Dividing fractions: using the shortcut	Geometry Lessons Lines, rays, and angles Measuring angles Parallel & perpendicular Acute, obtuse, and right triangles Angle sum of a triangle Equilateral & isosceles triangles Circles Symmetry Altitude of a triangle Polygons Perimeter Area of rectangles Area of right triangles Area of parallelograms Area of triangles Area versus Perimeter Angles in Polygons (PDF) Review: Area of Polygons (PDF) Surface Area (PDF)
Decimals Lessons Decimals videos Decimals (1 decimal digit) Decimal place value (1 decimal digit) Decimals (2 decimal digits) Decimal place value (2 decimal digits) Decimals (3 decimal digits) Add & subtract (1 decimal digit) Add & subtract (2 decimal digits) Add and subtract decimals — practice Comparing decimals Multiply a decimal by a whole number Multiply decimals by decimals Divide decimals—mental math Divide decimals by decimals Multiply and divide decimals by 10, 100, and 1000 Decimals review lesson	Percents Lessons How to teach proportions Percent - the basic concept Percentage of a number—mental math How to calculate a percentage of a number How to calculate percentages Basics of percent of change	General Four habits of highly effective math teaching Why are math word problems SO difficult for children? Hint: it has to do with a "recipe" that many math lessons follow. The do's and don'ts of teaching problem solving in math Advice on how you can teach problem solving in elementary, middle, and high school math. How to set up algebraic equations to match word problems Students often have problems setting up an equation for a word problem in algebra. To do that, they need to see the RELATIONSHIP between the different quantities in the problem. This article explains some of those relationships. Seven reasons behind math anxiety and how to prevent it Mental math "mathemagic" with Arthur Benjamin (video) Keeping math skills sharp in the summer Geometric vanish puzzles Science resources Short reviews of the various science resources and curricula I have used with my own children.

Rounding to the Nearest Hundred

See also