How can I tell if my numlock etc. buttons are active if I don't have a light?

Simplest method:
Type one character, then press 4 on num pad:

• If a character is typed in the field, then num lock is on.
  
• If cursor moves to left then num lock is off.

When num lock is off 4 works as left arrow key.

For Windows 10 with no num lock indicator light, you can go to SETTINGS, EASE OF ACCESS, KEYBOARD, USE OF TOGGLE KEYS, TURN ON SOUND so that a sound will alert you when caps lot, num lock, etc is on. I didn't realize this until after I brought my laptop home. I never thought to ask at Best Buy either. HP you did a disservice when you don't have this as a simple basic on the laptop for this model.