Rounding Off

Basic Electrical Engineering > Fundamental of Physics

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Rounding means making a number simpler but keeping its value close to what it was. The result is less accurate, less exact, but easier to use.

Rounding is used to simplify numbers. When rounding we are creating numbers that are approximate to their original value. The benefit to rounding is that it gives us numbers that are easier to work with. The downside to rounding is that the numbers will not always be exact.

Example: 73 rounded to the nearest ten is 70, because 73 is closer to 70 than to 80.

How to Round Numbers

When rounding, numbers can be rounded up or rounded down. This depends on the neighboring digit of the place value to be rounded.

What are the rules for rounding off numbers?

Here's the general rule for rounding:

If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up by 1.
Example: 57 rounded to the nearest ten is 60.
If the number you are rounding is followed by 0, 1, 2, 3, or 4, keep the rounding digit the same. This is called rounding down.
Example: 54 rounded to the nearest ten is 50.
When rounding to the left hand side of the decimal, all digits to the right side of the rounding digit will become 0 up until the decimal point.
When rounding to the right hand side of the decimal, drop all digits to the right of the rounding digit.

Exercise 1: Round the number 384306.4753 to the nearest ten.

Step 1: Circle the digit in the tens place value.
Step 2: Look to the neighboring digit on the right.
Step 3: Since the neighboring digit is greater than 5, the tens place value goes up by 1.
Step 4: Digits to the right of the tens place become 0 up until the decimal point.

Fig. 1: Exercise 1.

Exercise 2: Round the number 384306.4753 to the nearest ten thousand.

Step 1: Circle the digit in the ten thousands place value.
Step 2: Look to the neighboring digit on the right.
Step 3: Since the neighboring digit is less than 5, the ten thousands place value stays the same.
Step 4: Digits to the right of the ten thousands place value become 0 up until the decimal point.

Fig. 2: Exercise 2.

Do you have any questions?

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