Pull-down resistors on logic gate and decoder inputs?
CD40xx and HC74xx circuits do not include pullups or pulldowns on their inputs.

CD40xx and HC74xx inputs must not be allowed to float. They must always be driven with a defined logic level, from a logic output, from a pullup or pulldown, or a switch to ground or rail.

If CMOS inputs are allowed to float, they could end up in the middle linear region, which at best causes nonsense outputs, and at worst causes oscillation which draws excessive power and causes the chip to fail through overheating.

As CMOS needs very little (nominally zero) (leakage only) current, very large resistors can be used as pullups or pulldowns if speed is not an issue. 1Mohm 100k would draw only a few 10s of uA, and would be more than enough to keep all types of CD40xx inputs biassed properly (WRB says he's found one brand that specifies 5uA leakage max, though I've only seen 1uA in my (admittedly quick) survey of them).