Up to 1000

1
621
995
Rounding
Up or down?
Up to 1000
132
Chris Clements
2
ltdategt
Learning Objective
ltSteps to successgt
3
Rounding
Rounding is used to approximate or estimate.
Rounding is used to approximate or estimate.
Rounding is used to approximate or estimate.
Numbers can be rounded either up or down
Sometimes an exact number is not always required.
See the following examples
4
Rounding
The number of people who went to see William and
Kate after they got married could be rounded to
the nearest thousand (1000).
The number of sandwiches needed to be made for a
party may be rounded to the nearest ten (10).
5
Rounding
The number of nails in a box may be rounded to
the nearest 100.
The time it takes a car to get to a destination
may be rounded to the nearest minute.
6
Step 1 in the steps to success

1. Identify the units digit

2
2
7
9
9
5
4
6
4
2
4
5
5
8
8
3
7
4
4
4
4
3
3
continued
7
Take a look at these number lines.


126
120
122
130
125
127
128
129
121
124
123
If a number ends in a 5, 6, 7, 8 or 9
round up
So 125, 126, 127, 128 and 129 round up


200
300
205
206
207
208
209
204
203
202
201
If a number ends in a 1, 2, 3 and 4
round down
So 201, 202, 203 and 204 round down
continued
8
Now for the next 2 steps to success.
Do you think you know them?
2) Numbers that end with a 5, 6, 7, 8 or 9 round
up
3) Numbers that end with a 1, 2, 3 or 4 round
down


2
5
6
7
8
9
1
4
3
round up
round down
continued
9
Can you see if these numbers need to be rounded
up or down.


231 232 233 234 235 236 237 238 239
230
240
Is it closer to 230 or 240?
2
3
3
3
Does it end in a 1, 2, 3 or 4?
ROUND DOWN!


381 382 383 384 385 386 387 388 389
380
390
Does it end in a 5, 6, 7, 8 or 9?
Is it closer to 380 or 390?
3
5
5
8
ROUND UP!
continued
10


251 252 253 254 255 256 257 258 259
2
8
8
5
round up


781 782 783 784 785 786 787 788 789
7
3
8
3
round down


651 652 653 654 655 656 657 658 659
6
5
5
5
round up


951 952 953 954 955 956 957 958 959
9
5
4
4
round down
continued
11


3
7
1
8
2
2


6
9
9
2
2
5
Do these numbers
Round up
Round down
continued
12
Rounding up or down
Steps to success

• When rounding up or down there are three main
  things to remember
• 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
13
Activity
lttype heregt
14
Plenary
164
Find the number closest to 160 151, 164, 166, 154
Find the number closest to 420 411, 426, 414, 415
415
Which of these numbers give 80 when rounded to
the nearest 10?
75 and 83
74, 83, 75 and 86
Which of these numbers give  190 when rounded to
the nearest 10?
191, 186 and 193
191, 184, 186 and 193