On your birthday, you are moving ahead from one year to another in terms of numbers. This transition happens every year. These birthdays turn into anniversaries and celebrations in the future. So, the years make up decades and centuries. These centuries lead to a millennium. Have you ever thought about how many years is a millennium and what is 100,000 years called? In this way, it would be inevitable to know the differences and similarities in stating the facts of millennia vs millenniums. Continue reading!

**1. What do You call 100000 Years? What is a Million Years called?**

Years make up centuries. But one hundred thousand or one lakh years make up a **centum millennium**. You will get the centum millennium if you add the current year with 100,000. This is the Latin word used to describe the years. However, this term is rarely used to talk about years. This would have answered your query about what is 100,000 years called.

A million years is called **mega-annum** if you use the Latin word. Another word used to describe a million years is **epoch**. The epoch of our ancestors has passed away, and it is the epoch of the new generation. (Also read How Long is 1 Billion Seconds in Hours?)

**2. What is a Hundred Centuries called?**

Century denotes 100 years. If you live for 100 years on Earth, it makes a century. If you calculate hundred centuries, it is called **10,000 years**. Ten thousand years is called the **Decem millennium**. (Also read How Long is a Decade and a Century?)

**3. How many Years is a Millennium?**

A millennium includes **1000 years**. You heard it right. You are living in the third millennium. This is how the Cambridge Dictionary defines a millennium. Our Earth is still young when seen as a number. There are lakhs and millions of years to occur on Earth. Then there need to be billions of years. Also, check out Calendar 2022.

**4. How many Decades are in a Millennium?**

You might know that one decade is taken as 10 years. If ten years is a decade, how many years is a millennium? Yes, 1000 years denotes a millennium. That means **100 decades in one millennium**. A millennium is achieved when 100 decades are passed. Right now, it has been 202.2 decades. That means the time crossed 202 decades on Earth. (See What Year is it actually?)

**5. How many Months are in a Millennium?**

There are 12 months in one year, according to the calendar. But a millennium includes 1000 years. So, there are **12000 months in a millennium**. As you know, this is the 3^{rd} millennium. Therefore, the number of months in 3 millenniums would be calculated as 3 multiplied by 12000. It results in 36000 months. (See How did the Months get their names?)

**6. How many Days are in a Millennium?**

A day constitutes a year in a long time. In a normal year, you have 365 days in one year; in a leap year, it represents 366 days. If you take how many years is a millennium, you get 1000 years. Different results appear if you calculate the number of days in 1000 years. For the 1^{st} millennium, there were leap years after every 4 years, and years were noted in a Julian calendar. Thus, there were **365,250 days in the 1 ^{st} millennium**.

But in the 2^{nd} millennium, there were 237 leap days. Thus, the number of days in this millennium was calculated as **365,243** days. Finally, in the third millennium, you have 242 leap days. This makes it **365,242 days in the third millennium**. (Also read How Many Months Have 28 Days?)

**7. What is the Plural of Millennium? Millennia vs Millenniums**

When arguing millennia vs millenniums, the millennium constitutes millenniums. However, millenniums are called millennia. Millennia is the plural in the Latin sense of the word. But, in the 1930s, you could have found people using millenniums instead of millennia for 1000 years. Today, you can see that more people use the term **millennia as the plural of the millennium**. (See What is the plural of leaf? Is it leafs or leaves?)

**8. What is Year 2000 called?**

The year 2000 is termed as the **completion of two millennia**. It marks the beginning of the 21^{st} century.

**9. Are We in the 20**^{th} or 21^{st} Century? What will the Next Century be called?

^{th}or 21

^{st}Century? What will the Next Century be called?

This year you celebrated the birth of another year in the **21 ^{st} century,** yes, it is done like that. The 20th century ended in 1999, and the 21

^{st}century began in 2000. The century is always one ahead of the year. The 1800s to 1900s comes under the 19

^{th}century. Thus, the next century will start in 2100. This century would be known as the

**22**. (See What Century are We Living in Now?)

^{nd}century**10. How old is a Centennial?**

A centennial is always determined at the **end of 100 years**. It can be termed the 100^{th} anniversary or celebration of the completion of 100 years. A **centenary** is another word used to refer to a centennial.

Months and days constitute years. Each year contributes to a millennium. At the beginning of 2000, you completed the 2^{nd} millennium. The 3^{rd} millennium would end in 3000, giving birth to another millennium. The millennia of years, months, and days constitute different periods in different lives. What is called 100,000 years goes beyond the millennium. Once you understand this, you can ask your children or siblings about a millennium. Years can be counted to make centuries and centennials. We hope you got your answers to what is 100,000 years called and how many years is a millennium. (Also read How Many Years Equal A Score?)