Prime numbers, square and triangular numbers
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Types of numbers
A prime number is a whole number which can only be divided exactly (leaving no remainder) by exactly two different numbers, 1 and itself. We do not count 1 as prime, since it can only be divided by one number (itself).
A square number is a whole number which can be shown as a square pattern. Square numbers can be thought of as a number multiplied by itself, so 1 is also a square number (since 1 × 1 = 1).
A triangular number is a whole number which can be shown as a special triangular pattern, with each row one more than the row above.
