How do you round 638 to the nearest 10?

l l l l l l l l l l l

630 640638

Midpoint

In this lesson you will learn how to round to the nearest 10

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 the 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

410 420415

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

410

420415

410 420

415410 - 414 415-420

Let’s ReviewCore Lesson

Round 72 to the nearest 10.

70 80

Midpoint

75 l

Let’s ReviewCore Lesson

Round 368 to the nearest 10.

l l l l l l l l l l l360 370361 362 363 364 365 366 367 368 369

Benchmark Numbers

Midpoint365

Let’s ReviewCore Lesson

Rounding Down:132 130

Rounding Up:135 140

Let’s try another one!

In this lesson you have learned how to round to the nearest 10

by using a number line.

Let’s ReviewGuided Practice

Round 84 to the nearest 10.

Round 748 to the nearest 10.

Let’s ReviewExtension Activities

In your math journal discuss how you know when to round up to the greater ten.

Let’s ReviewExtension Activities

Draw a number line. Find the benchmark numbers for 43. Place 43 on the number line.

Would you round up or down?

Is 43 below or above the midpoint?

Let’s ReviewExtension Activities

Write 3 numbers that would round to 130.

Include numbers that round up and round down.

Let’s ReviewQuick Quiz

1). Which of these numbers would not round to 250?

246 252 249 254 255

2). Round 477 to the nearest ten.