That's only true if there are designated places for numbers and characters. There isn't, so every single spot can either be a number, upper case letter, lower case letter, or a symbol. 10 + 26 + 26 + 33 = 95
Here's my simplified 'proof'. The requirement that one must be a number does restrict the number of tries:
Simplified Example PW 3 char; one must be number, others can be number or Upper Case.
Compare to 3 char, number or Upper case, but no requirement for one to be number.
PASS#|Char 1|Char 2|Char 3|SUM|formula
||||38,880
1st PASS|10n|x36|x36|12,960|<< 10*36*36
2nd PASS|x36|10n|x36|12,960|<< 10*36*36
3rd PASS|x36|x36|10n|12,960|<< 10*36*36
w/o one number restriction:||||||
1st PASS|x36|x36|x36|46,656|<< 36*36*36
38,880 < 46,656
edit/add: Actually the difference is greater with the full 95 U/L/Symbol case and 3 char PW
270,750 < 857,375
further edit/add: It's actually greater savings than that. After the first pass, you know that char 1 cannot be a number, you already tested all combos. So the second and third passes for char 1 would be just 26x. Same for char 2 on the third pass. So only requires 28.37% as many scans.
PASS#|Char 1|Char 2|Char 3|SUM|
||||243,250
1st PASS|10n|x95|x95|90,250|
2nd PASS|x85|10n|x95|80,750|
3rd PASS|x85|x85|10n|72,250|
w/o one number restriction:||||||
1st PASS|x95|x95|x95|857,375|
-ERD50