/= Operator (Visual Basic)
Divides the value of a variable or property by the value of an expression and assigns the floating-point result to the variable or property.
variableorproperty /= expression
The element on the left side of the /= operator can be a simple scalar variable, a property, or an element of an array. The variable or property cannot be ReadOnly (Visual Basic).
The /= operator first divides the value of the variable or property (on the left-hand side of the operator) by the value of the expression (on the right-hand side of the operator). The operator then assigns the floating-point result of that operation to the variable or property.
This statement assigns a Double value to the variable or property on the left. If Option Strict is On, variableorproperty must be a Double. If Option Strict is Off, Visual Basic performs an implicit conversion and assigns the resulting value to variableorproperty, with a possible error at run time. For more information, see Widening and Narrowing Conversions (Visual Basic) and Option Strict Statement.
Overloading
The / Operator (Visual Basic) can be overloaded, which means that a class or structure can redefine its behavior when an operand has the type of that class or structure. Overloading the / operator affects the behavior of the /= operator. If your code uses /= on a class or structure that overloads /, be sure you understand its redefined behavior. For more information, see Operator Procedures (Visual Basic).