Question

1. michael saves $423 dollars a month for college.

a. about how much money will he have saved after 4 years?

Explanation:

Step1: Find number of months in 4 years

Since 1 year has 12 months, for 4 years, the number of months $n = 4\times12=48$ months.

Step2: Calculate total savings

Michael saves $423$ dollars per month. So the total savings $S$ is the savings per - month times the number of months. That is $S = 423\times48$.
We can estimate $423\approx400$ and $48\approx50$. Then $S\approx400\times50 = 20000$ dollars.

Answer:

About $\$20000$