Rounding to Nearest Tens Addition Strategy

Rounding to Nearest Tens Addition Strategy is a useful strategy when performing addition with numbers that are not multiples of ten. This strategy involves rounding each number to the nearest ten, adding the rounded numbers together, and then adjusting the sum if necessary to account for any rounding errors.

Here are the steps to perform addition using the Rounding to Nearest Tens Addition Strategy:

Example: Add 38 and 47 using the Rounding to Nearest Tens Addition Strategy.

Step 1: Identify the numbers: 38 and 47.

Step 2: Round each number to the nearest tens place.

For example, if you have the numbers 47 and 68, you would round 47 to 50 (since it’s closer to 50 than 40) and round 68 to 70 (since it’s closer to 70 than 60).

Step 3: Add the rounded numbers together.

In our example, 50 + 70 equals 120.

Step 4: Adjust for any rounding errors.

To adjust for rounding errors, calculate the difference between the original numbers and the rounded numbers. Then, add or subtract this difference from the sum.
For the numbers 47 and 68, the difference between 47 and 50 is 3, and the difference between 68 and 70 is 2. So, you need to subtract 3 + 2 = 5 from the sum of 120.
120 – 5 = 115

So, the sum of 47 and 68, rounded to the nearest tens, is 115.

This strategy is particularly useful when you want a quick estimate of the sum without having to deal with precise calculations. It can be handy for mental math and for quickly checking the reasonableness of your answer in more complex addition problems.

Step 5:

Undo the Rounding: To find the actual sum, you need to undo the rounding. Remember that you rounded 47 to 50 and 68 to 70.

Subtract 3 from 50 to undo the rounding for the first number: 50 – 3 = 47.
Subtract 2 from 70 to undo the rounding for the second number: 70 – 2 = 68.

Step 6:

Find the Actual Sum: Now that you’ve undone the rounding, you have the actual numbers:

47 + 68 = 115

To Rounding to Nearest Tens Addition Strategy 10, look at the units digit. If the units digit is 5 or more, round up. If the units digit is 4 or less, round down.

The last digit in 356 is 6. So we round it up to 360.
The last digit of 352 is 2. So we round it down to 350.
475 ends in a 5. We always round a 5 up. So 475 rounds up to 480.

What is Rounding to Nearest Tens Addition Strategy to 10, 100 and 500

Rounding to Nearest Tens Addition Strategy 10, 100, and 1000 allows us to approximate the size of a number.

We need to identify the number to the right of the tens, hundreds or thousands column depending on what we are rounding to.
If this number less than 5, round down.
If this number is 5 or more than 5, round up.

E.g.
Round 123 to the nearest 10.

The number to the right of the tens column is 3 which is less than 5 so we round down.
So 123 rounded to the nearest 123 is 120.

E.g.
Round 475 to the nearest 100.

The number to the right of the hundreds column is 7 which is more than 5 so we round up.
So 475 rounded to the nearest 100 is 500

Conclusion:

Rounding to the nearest tens addition strategy is a helpful technique for simplifying addition problems. By rounding the numbers first and then undoing the rounding after addition, you can easily find the actual sum. This approach is particularly useful when dealing with numbers that are close to multiples of ten.