Information collected by Anda

These numbers can be arranged

to look like squares:

1, 4, 9, 16, 25, 36, 49, 64, 81, 100,

…

A curious propertyappears when we

subtract a squarednumber from its

successor :4 – 1 = 39 – 4 = 516 – 9 = 7

25 – 16 = 9, …The drawing shows

you why!

These numbers can

be arranged to look

like triangles:

1, 3, 6, 10, 15, 21, 28, 36, 45, 55, …

A curious property appears when we

add two successive trianghular

numbers: the result is always a squared

number!

1 + 3 = 4 3 + 6 = 9

6 + 10 = 1610 + 15 = 25, …