Multiplication sign
A multiplication is so obvious that we sometimes omit the multiplication sign.
Example 1
The calculation 4 × 7 = 28 can be written as
because parentheses are an implicit multiplication.
Example 2
The calculation 23 × e × π = 196.4138… can be written as
because letters always form a multiplication.
Example 3
The calculation 2√2 × 2√2 = 8 may be performed as
because a radical sign is an implicit multiplication.