Which of these numbers round to 600?

568 651509

l l l l l l l l l l l550 650600

In this lesson you will learn how to round to the nearest 100 by using a number line.

Let’s ReviewLet’s Review

l l

150 160I I I I I I I I I

Benchmark Numbers

151 152 153 154 155 156 157 158 159

l l

100 200I I I I I I I I I

110 120 130 140 150 160 170 180 190

Let’s ReviewLet’s Review

Rounding - To find a number that is close to a given number.

l l l l l l l l l l lBakery

Morgan

Ashley Pizza

Let’s ReviewLet’s Review

I I I I I I I I Il l

400 500

Benchmark Numbers

410 420 430 440 450 460 470 480 490

What is a midpoint?

The midpoint marks the

middle of the line.

Let’s ReviewA Common Mistake

Thinking that the increments on a number line always signify counting by

ones.

l l l l l l l l l 300 400 310 320 330 340 350 360 370 380 390

Let’s ReviewA Common Mistake

Knowing when to round up or round down.

It is important to consider the number size and benchmark numbers when

rounding.

Let’s ReviewCore Lesson How can I use benchmark numbers and midpoints to help

me round?

l l l l l l l l l l l

1,400 1,5001,450

Numbers less than the midpoint round down.

Numbers the same as or greater than the midpoint round up.

Let’s ReviewCore Lesson

l l l l l l l l l l l

1,400 1,5001,450

1,400 1,500

1,4501,400-1,449 1,450 –

1,499

Let’s ReviewCore Lesson

Round 349 to the nearest 100.

300 400Midpoint

l350

Let’s ReviewCore Lesson

Round 1,472 to the nearest 100.

l l l l l l l l l l l1,400

1,5001410 1420 1430 1440 1450 1460 1470 1480 1490

Benchmark Numbers

Midpoint1,450

In this lesson you have learned how to round to the nearest 100 by using a number line.

Let’s ReviewGuided Practice

Round 2,639 to the nearest hundred.

Let’s ReviewExtension Activities

In your math journal, explain why 395 rounds to 400 when rounding to the nearest ten and the nearest hundred.

Let’s ReviewExtension Activities

Write 5 numbers that would round to 700 when rounding to the nearest 100.

Think of numbers that require rounding up as well as numbers that round down.

Let’s ReviewExtension Activities

Draw a number line with 1,200 and 1,300 as the benchmark numbers.

What is the midpoint?

Where would 1,262 fall on the number line?

Let’s ReviewQuick Quiz

1). Which of the following numbers do not round to 1,700?

1,734 1,656 1,7091,649

2). Round 883 to the nearest 100.