## Step (1)

The table below shows

all the whole numbers

in the left column

&

the respective triangular numbers

generated from these

in the right column.

##### Triangular Numbers Table

##### Base

number

##### Triangular

number

0

(0 x 1)/2 = 0

1

(1 x2 )/2 = 1

2

(2 x 3)/2 = 3

3

(3 x 4)/2 = 6

4

(4 x 5)/2 = 10

5

(5 x 6)/2 = 15

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(0 x 1)/2 + (1 x 2)/2 = 0 + 1 = 1 = 12

(1 x 2)/2 + (2 x 3)/2 = 1 + 3 = 4 = 22

(2 x 3)/2 + (3 x 4)/2 = 3 + 6 = 9 = 32

(3 x 4)/2 + (4 x 5)/2 = 6 + 10 = 16 = 42

(4 x 5)/2 + (5 x 6)/2 = 10 + 15 = 25 = 52

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one can deduce that in general

in to the 2nd. power is

the sum of 2 triangular numbers

per the formula shown below: