# Why does 78 minus your age plus 40 work?

**does 78 minus your age plus 40**equal the last two digits of

**your**birth date? Transpose the instructions and add

**40**to

**78**first. This gives you 118, the number of years that have elapsed since this day in 1900 (today is July 25, 2018).

**Subtracting**this from 118 gives 80, the junior two digits of

**your**year of birth.

Regarding this, why does 79 minus your age plus 40 work?

**79**+**40**=119. That's the number of years from 1900 to 2019. **Subtract your age** from 119 and you'll get the year you were born. It only **works** well at the end of the year however, because at that point, most people will have had a birthday in the current year.

Secondly, how do you figure out someone's age trick? To do a number **trick** to guess **someone's age**, start by asking them to use a **calculator** to multiply the first number of their **age** by 5. Then, have them add 3 before doubling the answer. Next, they should add the second number of their **age**. Finally, tell the person to subtract 6 and the answer will be their current **age**.

Subsequently, one may also ask, how does the birthday math trick work?

**"Threes" Birthday Math Trick**

- Enter the secret number.
- Multiply by 3.
- Add the secret number, then subtract 5.
- Multiply by 3, then multiply by 3 again.
- Add the secret number, then subtract the number of their favourite month (you don't have to know what month that is!)
- Multiply by 3, then multiply by 3 again, and then again a third time.

What is it called when you are the same age as the year you were born?

A Beddian Birthday occurs when the **age** a person is turning, is the **same** number as the last two digits of their birth **year**. The Beddian birthday is named for NYC firefighter Bobby Beddia who noted this coincidence. Someone **born** in 2015, will experience their Beddian Birthday when **they** are 15!