# Multiplication Signs

There are multiple versions of the multiplication sign.

Classic Multiplication Sign
Sign:  ×
3 × 5 = 15

Alternative Multiplication Signs

In order to avoid confusion between the classic multiplication sign × and the letter x (often used in algebra), alternative multiplication signs were invented.

Sign:  ·
3 · 5 = 15

Sign:  *
3 * 5 = 15

Invisible Multiplication Signs

When a number is immediately adjacent to a letter or parenthesis, an invisible multiplication sign is in force.
3a = 3 × a
3(a) = 3 × a
3(5) = 3 × 5

When a number is immediately adjacent to an operation in parenthesis, an invisible multiplication sign is in force.
2(a + 4) = 2 × a + 2 × 4
2(a – 4) = 2 × a – 2 × 4

When a letter is immediately adjacent to a number, letter, or parenthesis, an invisible multiplication sign is in force.
a3 = a × 3
ab = a × b
a(3) = a × 3
a(b) = a × b

When a letter is immediately adjacent to an operation in parenthesis, an invisible multiplication sign is in force.
a(b + 4) = a × b + a × 4
a(b – 4) = a × b – a × 4

When π is immediately adjacent to a number, letter or parenthesis, an invisible multiplication sign is in force.
3π= 3 × π
aπ = a × π
π(3) = π × 3
π(a) = π × a

When the root sign    is immediately adjacent to a number or letter, an invisible multiplication sign is in force.
53  =  5 × √3
a3  =  a × √3