Difference between liǎng and èr

I remember that "er" (二) is the standard way to say the number two, used in counting and mathematics. For example, when counting one, two, three, it's "yi, er, san." Also, in numbers like twenty (二十 - er shi) or two hundred (二百 - er bai), "er" is used.

On the other hand, "liang" (两) is used more as a measure word or for quantities. It's often used before classifiers. For instance, "two people" would be "liang ge ren" (两个人), not "er ge ren." So "liang" is used when specifying a quantity of something, especially with measure words.

Wait, but there might be exceptions or specific contexts where one is preferred over the other. For example, in certain expressions or idioms, maybe "er" is used even when referring to quantities. Also, in some compound words, like telephone numbers or addresses, "er" would be used. Like room 202 would be "er ling er."

I should also mention that "liang" is used in informal contexts more for counting objects, while "er" is the numeral in formal or mathematical contexts. Additionally, "liang" can't be used in ordinal numbers; for second, it's "di er" (第二), not "di liang."

Need to make sure I don't mix up their usages. Let me check if there are other cases. Oh, right, when expressing approximations, like "a couple of days," it's "liang tian" (两 天). Also, in some measurements, like "two kilometers," it's "liang gongli" (两公里).

So the main points are: "er" is the numeral used in counting, math, and ordinal numbers, while "liang" is used with measure words and quantities. They aren't interchangeable in most cases. Got it. Now, structure this into a clear, concise answer with examples.

First, I need to confirm whether this approach is accurate and helpful. The user wants a clear way to remember the difference. Using parenthetical notes like "(of something)" for 两 makes sense because 两 is used with measure words and quantities. However, I should check if this might be oversimplifying.

I should also consider if there are exceptions or additional nuances. For example, 二 is used in ordinal numbers and counting, while 两 is for general quantities. Maybe the user's method works for basic vocabulary, but they should be aware of contexts where 两 isn't used, like in numbers beyond 2000 where 两 is sometimes used instead of 二, like 两千 for 2000.

I should suggest that their method is a good starting point but mention that there are more nuances. Also, providing examples would help solidify the distinction. Maybe warn them about cases where 二 is used in measures, like 二两 (èr liǎng) meaning "two taels," which is an exception.

So, the answer should validate their approach, offer a slightly refined suggestion, and highlight exceptions. Make sure to keep it encouraging and clear.