Array/area models
Use an Array model to multiply 20 x 14
...
Use compatible numbers to estimate 28 x 19
25 x 20 = 500
draw a 14 x 12 area model/array
168
13 x 55
(10+3) x (50+5)
(10x50)+(3x50)+(10x5)+(3x5)
= 715
List the partial products for 16 x 35
30,50,180,300
10 x 23
230
29 x 31
30 x 30 = 900
14 x 32
448
12 x 19
228
18 x 34
32,40,240,300
16 x 20
320
73 x 18
75 x 20 = 1500
56 x 17
952
62 x 11
682
53 x 17
21,350,30,500
10 x 17
170
19 x 31
20 x 30 = 600
26 x 63
1,638
38 x 12
456
22 x 66
12,120,120,1200
18 x 30
540
42 x 49
40 x 50 = 2,000
19 x 51
969
45 x 23
1,035
64 x 86
24, 360, 320,4800