800 300

100700 Chris Clements

Rounding

To the nearest 100

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Learning Objective:

<Steps to success>

Rounding Rounding Rounding

In this lesson we are looking at rounding numbers to the nearest

100.

Rounding

Rounding is used to approximate or estimate.

Rounding whole numbers

Rounding whole numbers

Can you remember how to round numbers to the

nearest 10? Identify the units digit.

If the units digit is a 1, 2, 3 or 4 we round down.

If the units digit is a 5, 6, 7, 8, or 9 we round up.

continued

There is a similar pattern for rounding numbers to the

nearest100

1) Identify the tens digit.

Onto the next step.

continued

2) If the tens digit is a 0, 1, 2, 3 or 4 we round down to the nearest 100.

continued

510 520 530 540 550 560 570 580 590

Is it closerto 500 or 600?

Is it closerto 400 or 500?

410 420 430 440 450 460 470 480 490

Can you see that the units digit is not important when rounding numbers to 100?

Onto the final step.

continued

3) If the tens digit is a 5, 6, 7, 8 or a 9 round up to the next hundred.

continued

510 520 530 540 550 560 570 580 590

Is it closerto 500 or 600?

Is it closerto 600 or 700?

610 620 630 640 650 660 670 680 690

Remember if a number ends in -50, although it is exactly halfway between the two hundred values we still round up!

Lets have ago at rounding to the nearest 100.

continued

310 320 330 340 350 360 370 380 390

Is it closerto 300 or 400?

610 620 630 640 650 660 670 680 690

Is it closerto 600 or 700?

710 720 730 740 750 760 770 780 790

Is it closerto 700 or 800?

And more…

110 120 130 140 150 160 170 180 190

Is it closerto 100 or 200?

810 820 830 840 850 860 870 880 890

Is it closerto 800 or 900?

910 920 930 940 950 960 970 980 990

Is it closerto 900

or 1000?

continued

Now without the number line!

Last three…

continued

Activity

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Learning Objective:

Steps to success

1) Identify the tens digit. 2) If the tens digit is a 0,1, 2, 3 or 4 we

round down to the nearest 100.

3) If the tens digit is a 5, 6, 7, 8 or a 9 round up to the next hundred.

Plenary

Match these numbers to the nearest 100.

428700

342100

712400

51300

170490

320420

390

Choose 2 cards that when added

together round to 500.

How do you round numbers to the nearest thousand (1000)?

170 and 320 = 490