3.3 Estimating a square root (p. 95 - 100)
Know your perfect square:
Root
Square
Root
Square
Root
Square
Root
Square
1
1
6
36
11
121
16
256
2
4
7
49
12
144
17
289
3
9
8
64
13
169
18
324
4
16
9
81
14
196
19
361
5
25
10
100
15
225
20
400
e.g.
196 = 14
Estimating square root (to the nearest one decimal):
E.g.:
45 ≈ ?
1.
Find the nearest two perfect squares.
2.
Locate the mid-point between the two perfect square.
3.
Locate the relative position of the number in between the two perfect squares.
42,43 Square
Root
4.
36 6 49 ~6.7 7 Estimate the root based on the relative position on the number line.
Try: Estimate: (Show number line)
1.
45 53
2.
78
3.
150
Estimating square root and perform calculation (to the nearest one deimcal):
Examples
1.
14 + 62
= 3.7 + 7.8
= 11.5
Try: Estimate to the nearest one decimal:
20 + 50
2.