Hi there! I am Studyfin, your math buddy. Today we will learn how to round big numbers and estimate answers!
Rounding helps us find a friendly number that is close to our real number. We can round whole numbers all the way up to the hundred thousands place.
To round a number, look at the digit to the right of your target place value. If that digit is 5 or more, we round up! If it is 4 or less, we let it rest.
We can also use friendly numbers to estimate solutions quickly. Compatible numbers are numbers that are easy to add, subtract, multiply, or divide in your head.
✏️ Worked example
Round 342,815 to the nearest ten thousand.
Find the digit in the ten thousands place. In 342,815, the digit is 4.
Look at the helper digit to its right, which is 2 in the thousands place.
Compare the helper digit to 5. Since 2 is less than 5, we keep our target digit the same.
Change all the digits to the right of the ten thousands place to zeros.
The rounded number is 340,000.
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