• ← NumberQ
• → OddQ

NumericQ

WMA link

NumericQ[expr]

tests whether expr represents a numeric quantity.

• • NumericQ[2]

• • NumericQ[Sqrt[Pi]]

• • NumberQ[Sqrt[Pi]]

It is possible to set that a symbol is numeric or not by assign a boolean value
to ``NumericQ``

• • NumericQ[a]=True

• • NumericQ[a]

• • NumericQ[Sin[a]]

Clear and ClearAll do not restore the default value.

• • Clear[a]; NumericQ[a]

• • ClearAll[a]; NumericQ[a]

• • NumericQ[a]=False; NumericQ[a]

NumericQ can only set to True or False

• • NumericQ[a] = 37