In the beginning, rounding whole numbers may not make logical sense. After all, the goal of math is to land at the exact right answer. However, rounding is an essential function in math, and there are many different places they pop up. Before beginning our overall test preparation, let’s talk about rounding.
GED is a registered trademark of the American Council on Education, neither of which are affiliated with this site.
Why Rounding Matters
Rounding whole numbers has been around for as long as math has been. In principle, rounding makes math easier to understand and communicate. It also helps people do math in their heads, which is essential since mass education and literacy is a relatively recent innovation.
In everyday life, most people round without thinking about it. The grocery store is a familiar setting since everyone has a budget in mind. Over the course of a shopping trip, each item added to the cart also gets its price rounded to the nearest dollar. These figures are then added to the mental total. In this case, the rounding helps us account for sales tax. Rounding whole numbers for math problems is just a little more complicated.
A Review of Place Values
On a math GED® test, the place the answer will be rounded to will be specified. For whole numbers, the questions will define things like rounded to the nearest hundred or the nearest ten. Therefore, let’s talk about places.
Places are always counted from the ones spot, which is the spot furthest right as you’re looking at a number. When you get to decimals, we’ll talk more on places. For right now, focus on finding the ones spot.
From the ones spot, to the left is the ten and hundred spots. Then, most people write in a comma to help them keep their place. From there, commas should appear every three numbers. Again, it’s important to count this from the left, not the right.
Apart from scientific notation, most of the numbers you’ll see are under a million. From left to right, that’s ones, tens, hundreds, thousands, ten thousands, hundred thousands, and millions. You notice there is a naming pattern that repeats every three numbers, yes? That lets you talk about numbers as long as you know which set of three it is, from thousands to quadrillions.
The Steps of Rounding Whole Numbers
Rounding whole numbers requires finding the correct place and using the place to the left to determine how the rounding goes. However, it takes practice to do without thought, so don’t get discouraged if this doesn’t come quickly.
The first step is identifying what place the problem is asking about. Without this information, you cannot accurately round.
The second step is identifying the number one spot to the right of the place mentioned in the problem. This number determines whether you are going to round up or down. Look at the number and think of the phrase “5 or above, give it a shove. 4 or below, let it go.”
Remember, you do not change the number one spot to the right. That number and everything after that becomes 0s. You’re changing the number in the original place value mentioned in the problem. It either stays the same or goes up 1 value based on the phrase mentioned.
Rounding Whole Numbers Examples
It’s easy to talk about rounding whole numbers, but let’s do a few examples too.
Let’s say the problem wants you to round 1,356 to the nearest hundred. That means the number that’s going to change is 3, and the number one spot to the right is 5. In the phrase, that falls under “5 or above, give it a shove.” Therefore, the 3 will become a 4. Our final answer would be 1,400.
Now for another. The problem says 167,398 needs to be rounded to the nearest ten thousand. That means the ten thousands spot is the 6, and the number immediately to the right is 7. In the phrase, that falls under “5 or above, give it a shove.” Therefore, the 6 will become a 7. Our final answer would be 170,000.
For our final example, let’s say the problem is 1,356, 849 and we need to round to the nearest million. The number we’re looking at is 1, and the number to the right is 3. In the phrase, that falls under “4 or below, let it go.” That means the number 1 does not change. The final answer would be 1,000,000.