A Pd object only fires from its leftmost (hot) inlet; other inlets are cold and merely store

When an object has several inlets you must feed them right to left. Only the far-left inlet is ‘hot’: input there triggers the object to compute and emit output. The other inlets are ‘cold’: data entered into them is stored but causes no immediate output. So to add two numbers correctly you send the right (cold) operand first, then the left (hot) operand, which fires the sum. Ignoring this ordering is the classic Pd bug - the object computes using a stale cold value. This right-to-left, hot-inlet-last discipline recurs throughout Pd.

Examples

For [+ ]: feed 3 into the right (cold) inlet, then 5 into the left (hot) inlet -> outputs 8. Feeding the left inlet first outputs the sum with the old right value.

Assessment

You want to compute a*3+2 reliably. In what inlet order must the values arrive, and which single inlet actually triggers output? Explain what goes wrong if you reverse it.