Opposite Corners
If you start putting numbers into a grid that is 10 columns
wide then you get this layout:
1
2
3
4
5
6
7
8
9
10
11
21
31
12
22
32
13
23
33
14
24
34
15
25
35
16
26
36
17
27
37
18
28
38
19
29
39
20
30
40
41
…
42
…
43
…
44
…
45
…
46
…
47
…
…
…
…
…
…
…
If I draw a 3 by 3 square around 9 of the numbers as shown
then I have:
13
14
15
23
24
25
33
34
35
Adding the four corners gives an answer of 96.
13 + 15 + 33 + 35 = 96
Always using 10 Columns:
1. Put the square in other positions on a grid with 10
columns and find the total when the four corners are
added.
2. Add the four numbers along the middle of each size
3. Add each row or column
4. Add opposite corners together
5. Add the 9 numbers and compare to the middle number or
to the top left number …
6. Change the size of the square. What about rectangles?