บทที่ 2 (Lesson 2) — Counting 1-100

Introduction

Thai counting follows a logical pattern, but with a few important exceptions that every learner must know. The rules for teens (11-19) and the word for 20 are different from what you might expect.

The Basic Pattern

Thai numbers follow a place-value system like English:

• Tens place + สิบ (sìp) = "ten"
• Ones place = the digit

Example: 35 = สาม (3) + สิบ (10) + ห้า (5) = สามสิบห้า (sǎam-sìp-hâa)

The Teens (11-19): Special Rule #1

For 11-19, Thai uses สิบ (sìp) first, then adds the ones digit. But there's a catch:

หนึ่ง becomes เอ็ด (èt) when it's not alone.

Key rule: หนึ่ง (nʉ̀ng) is only used when it stands alone. In compounds, it becomes เอ็ด (èt).

Twenty: Special Rule #2

Here's the second exception: 20 is NOT สองสิบ!

20 = ยี่สิบ (yîi-sìp)

Why? Historical reasons — ยี่ is an older word for "two" that survives only in this context.

The Regular Tens (30-90)

After 20, the pattern is regular:

Building Any Number 1-99

Formula: [tens word] + สิบ + [ones word]

Remember:

• Use เอ็ด for 1 in compounds (21, 31, 41...)
• Use ยี่สิบ for 20-29
• Everything else is regular

Key Points

1. เอ็ด replaces หนึ่ง: Always in compound numbers (11, 21, 31...)
2. ยี่สิบ for 20: Never สองสิบ
3. สิบ = 10: The building block for all two-digit numbers
4. Pattern is logical: Once you know the exceptions, it's predictable

Common Mistakes

• ❌ ยี่สิบหนึ่ง → ✓ ยี่สิบเอ็ด (21)
• ❌ สองสิบ → ✓ ยี่สิบ (20)
• ❌ สามสิบหนึ่ง → ✓ สามสิบเอ็ด (31)

Practice Counting

Try saying these out loud:

• 15, 25, 35, 45, 55
• 11, 22, 33, 44, 55
• 19, 29, 39, 49, 59

Practice Exercises

What's Next

In Lesson 3, you'll learn large numbers — hundreds, thousands, and millions — including how Thai groups numbers differently than English.