One physical idea seeds a whole family: striking, a blow landing. From the literal hit comes the person a blow has broken (the disabled person) and the abstract state of being broken (disability). Then the same root jumps to money: to "strike off" an amount is to deduct it, so a salary deduction is, etymologically, a blow taken off the total. Each word here is verified against pealim, niqqud included.
The same root runs through the verb system. Each binyan is a voice: it bends the one idea into active, passive, causative or reciprocal. Tap to hear.
This is a weak (final-ה) root, so the pa'al "to strike" is supplied by the hif'il form לְהַכּוֹת in everyday Hebrew. The pi'el carries the financial sense "deduct" (strike an amount off). The other binyanim are not lexicalized for this root.
Same root letters, different noun moulds (mishkalim). The mould tells you the function: who does it, the act of doing it, or the thing produced.
Strip the prefixes, suffixes and vowels. Three consonants remain, and the meaning lives there.