I’m surprised more people don’t know these quick, easy brain hacks!

To convert **hourly wage to annual salary**, multiply by 2 and add 3 zeros. ($15/hr = ~$30,000/year)

To convert **annual salary to hourly wage**, divide by 2 and remove 3 zeros. ($30,000/year = ~$15/hr)

To find the **return of an investment in the US stock market** over a period adjusted for inflation and including taxes:

- For
**one year**, add 3%. ($1000 one year later = ~$1030) - For
**three years**, add 10% ($1000 three years later = ~$1100) - For
**five years**, add 15% ($1000 five years later = ~$1150) - For
**ten years**, add 30% ($1000 ten years later = ~$1300)

(Assuming 9% interest compounded yearly, a 30% tax rate, and a 3% inflation rate)

**Got any more simple mental calculations or conversions? Let me know in the comments!**