Download Round 2-Digit and 3-Digit Numbers

Round 2-Digit and
3-Digit Numbers
CA Standards
NS 1.4 Round off numbers
to 10,000 to the nearest ten,
hundred, and thousand.
Objective Round 2-digit and 3-digit numbers
to the nearest ten or hundred.
NS 1.0 Students understand the
place value of whole numbers.
Also KEY NS 1.3 , MR 1.1,
MR 2.3, MR 2.4, MR 2.5
round
You can use what you know about place value
to round numbers and estimate quantities.
A theater company performed 154 shows.
Give an estimate of the number of shows
by rounding to the nearest hundred.
estimate
Different Ways to Round
Way 1 Use rounding rules.
1
Underline the digit in the
place you are rounding to.
hundreds place
2
Circle the digit to the right
of the underlined digit.
circled digit
3
If the circled digit is 5
or greater, increase the
underlined digit by 1.
If the circled digit is less than
5, leave the underlined digit
unchanged.
Then replace the digits to
the right of the underlined
digits with zeros.
Houghton Mifflin California Math, Lesson Transparency 2.3
Copyright © Houghton Mifflin Company. All rights reserved.
Use with Chapter 2, Lesson 3
154 rounds to 200.
Way 2 Use a number line.
2OUNDSTO
ISHALFWAY
Find 154 on the number line.
154 is closer to 200 than to 100.
So, 154 rounds to 200.
Solution: The theater company performed about 200 shows.
Another Example
Round 263 to the nearest ten.
26 3
2OUNDSTO
260.
3 is less than 5. So,
263 rounds to 260.
Round the number to the nearest ten and the
nearest hundred.
1. 466
2. 765
3. 45
To what place am
I rounding?
4. 71
Guided Problem Solving
Use the questions to solve this problem.
5. The show is about to start. There are
273 people to be seated. Estimate to the
nearest ten the number of people waiting.
a. Understand What are you asked to find?
b. Plan Choose a way to solve the problem.
c. Solve Round and show your work.
d. Look Back Solve the problem another
way. Did you get the same answer?
Math Talk
Will says that 395 rounded to the
nearest ten is the same as 395 rounded to the nearest
hundred. Is he right or wrong? Explain your answer.
Houghton Mifflin California Math, Lesson Transparency 2.3
Copyright © Houghton Mifflin Company. All rights reserved.
Use with Chapter 2, Lesson 3