You're working on building your emergency fund. Your total living expenses are

\[\$3{,}900\] per month and you're hoping to save enough for three months' worth of expenses. You are currently saving
\[\$900\] each month.
How long will it take you to fully fund your emergency fund?

To find out how long it will take to fully fund the emergency fund, we need to determine the total amount needed for three months of expenses and then divide that by the monthly savings.

The total amount needed for three months of expenses can be calculated by multiplying the monthly expenses by three:
\[3,900 \times 3 = 11,700\]

Now, we can divide the total amount needed by the monthly savings to find out how many months it will take to fully fund the emergency fund:
\[11,700 / 900 = 13\]

Therefore, it will take 13 months to fully fund the emergency fund.