## Question

###### A number in ALGOL (excluding the exponential form) is defined as follows: $$\langle\text { number }\rangle :=\langle\text { decimal number }\rangle :\langle\text { sign }\rangle\langle\text { decimal number }\rangle$$ $\langle\text { decimal number }\rangle : :=\langle\text { unsigned integer }\rangle \langle\text { unsigned integer }\rangle |$ $$\langle\text {unsigned integer}\rangle. \langle\text {unsigned integer}\rangle$$ $$\langle\text { unsigned integer }\rangle : :=\langle\text { digi

A number in ALGOL (excluding the exponential form) is defined as follows: $$\langle\text { number }\rangle :=\langle\text { decimal number }\rangle :\langle\text { sign }\rangle\langle\text { decimal number }\rangle$$ $\langle\text { decimal number }\rangle : :=\langle\text { unsigned integer }\rangle \langle\text { unsigned integer }\rangle |$ $$\langle\text {unsigned integer}\rangle. \langle\text {unsigned integer}\rangle$$ $$\langle\text { unsigned integer }\rangle : :=\langle\text { digit }\rangle :\langle\text { unsigned integer }\rangle\langle\text { digit }\rangle$$ $$\langle\text { digit }\rangle : := 0|1| 2|3| 4|5| 6|7| 8 | 9$$ $$\langle\operatorname{sign}\rangle : :=+|-$$ Use this grammar to answer Exercises $60-67$. Determine if each is a valid ALGOL number. $$234.$$