# 3 Decimals

```Each digit in a number has a value that depends on its place in that number i.e. its place
value
Four hundred and fifty two point nine four five
For example:
452.945
400
Hundreds
100 s
50
tens
10 s
2
units
1s
0.9
tenths
1/10 s
0.005
0.04
hundredths thousandths
1/1000 s
1/100 s
Imagine if I put a 5 at the beginning of the number. What would each number
represent?
5452.495
Unit 3: Decimals
Today: Place Value and Ordering
02/10/17
LO’s: I can write decimals and understand place value
I can order decimals
Starter – What goes with these to make 1?
0.5
0.6
0.2
0.25
What goes with these to make 10?
2.4
4.8
7.3
1.9
8.41
3.82
Ordering Decimals
0.2
0.25
0.52
0.34
0.355
0.02
1.25
Ordering Decimals
0.2
0.25
0.52
0.34
0.355
0.02
0.200 0.250 0.520 0.340 0.355 0.020
Ans: 0.02
0.2
0.25
0.34
0.355
0.52
1.25
1.25
1.25
Unit 3: Decimals
Today: Place Value and Ordering
2/10/17
LO’s: I can add / subtract decimals
Starter – Order these decimals from smallest to largest
2.
3.
4.
5.
0.94
4.71
3.65
0.3
0.91
3.65
3.69
0.35
0.97
3.83
3.6
0.5
0.9
4.91
3.06
0.53
0.89
3.15
3.46
0.355
0.8
4.09
3.4
0.03
0.907
3.5
3.1
0.61
2.
3.
4.
5.
2.
3.
4.
5.
0.94
4.71
3.65
0.3
0.8
3.15
3.06
0.03
0.91
3.65
3.69
0.35
0.89
3.5
3.1
0.3
0.97
3.83
3.6
0.5
0.9
3.65
3.4
0.35
0.9
4.91
3.06
0.53
0.907
3.83
3.46
0.355
0.89
3.15
3.46
0.355
0.91
4.09
3.6
0.5
0.8
4.09
3.4
0.03
0.94
4.71
3.65
0.53
0.907
3.5
3.1
0.61
0.97
4.91
3.69
0.61
“Star questions” – CHALLENGE
11.57 – 9.82 – 2.53
26.5 + 1.85 +208.3
Unit 3: Decimals
16/10/17
Rounding
LO’s: I can round to 1dp and 2dp
Starter – Can you round these numbers to the nearest 10?
74
23
35
67
19
123
288
423
194
198
694
1148
2357
1484
3495
Rounding Decimals
Look right next door.
4 or less, just ignore.
5 or more, add 1 more.
Look right next door.
4 or less, just ignore.
5 or more, add 1 more.
Rounding Decimals
Round these to the nearest 1 decimal place:
1.
5.349
2.
14.23
3.
8.62
4.
472.450
Round these to the nearest
2 decimal places:
5.
13.983
1.
5.349
6.
6.544
2.
14.233
7.
93.15
3.
8.6251
8.
9.897
4.
472.410
9.
645.07
5.
13.9839
10.
32.545
Extension
PRACTICE PRACTICE PRACTICE! 
PRACTICE PRACTICE PRACTICE! 
two decimal places:
B)
Rounding to decimal places
Complete this table:
to the nearest
whole number
to 1 d.p.
to 2 d.p.
to 3 d.p.
63.4721
63
63.5
63.47
63.472
87.6564
88
87.7
87.66
87.656
149.9875
150
150.0
149.99
149.988
3.54029
4
3.5
3.54
3.540
0.59999
1
0.6
0.60
0.600
Rounding to decimal places
Complete this table:
to the nearest
whole number
63.4721
87.6564
149.9875
3.54029
0.59999
to 1 d.p.
to 2 d.p.
to 3 d.p.
EASY 
MODERATE
CHALLENGING 
CHALLENGING
```