• 増加ぞうか — increase / growth
• 増強ぞうきょう — reinforcement
• 増税ぞうぜい — tax increase
• 増員ぞういん — increase in personnel
• 増築ぞうちく — building extension
• 増幅ぞうふく — amplification
• 増進ぞうしん — promotion (of health, efficiency)
• 増量ぞうりょう — increased quantity

The old form of 増 combines elements for "dirt" (土), "straight vertical structure" (目-based), and a phonetic element 曾 (ソウ), forming a character that originally signified “to add” or “multiply.” According to KADOKAWA’s new character dictionary, the current form used in education follows the simplified shape but preserves the original meaning of "to increase or multiply."

人口じんこうが 年々ねんねん 増ふえている。
The population is increasing year by year.

予算よさんが 増加ぞうかした。
The budget increased.

The on-yomi ゾウ (zou) is widely used in compound nouns. The kun-yomi ふえる and ふやす appear in general-use phrases like 人数にんずうが増ふえる (the number of people increases). The transitive/intransitive pair is also a key learning point.