This was a deliberate change in v24.
In v23, if you wanted to enter an alt-keypad combination (i.e., holding down the alt key and pressing 0-9 one or more times in order to insert a specific key) it had to be done on the keypad, not using the 1 - 0 keys on the top row of the keyboard. This caused a lot of grumbling from users who either didn't have a numeric keypad (small laptops or mini keyboards), or who didn't want to switch their keypad in & out of numeric mode (with the Num Lock key).
In v24, you can enter alt-keypad combinations either with the keypad or by using the numeric keys on the top of the keyboard. This means that there's no special keys "Alt-0" through "Alt-9" anymore; they're interpreted as requests for the ASCII values 0 - 9.