Estimating and Adding Numbers

In estimating the sum, what do you do when the addends do not have the same number of digits?

• Round off the addends to the highest place value then add.

• Round off the addends to the highest place value of the lesser number then add.

• Round off both addends to the lowest place value.

• Add both addends directly.

Based on the rules for rounding off numbers, which is the best example of a good estimate for 487 + 36?

• 490 + 40

• 500 + 40

• 500 + 30

• 490 + 30

What are the possible addends if the estimated sum is 500?

• 566 and 122

• 430 and 211

• 352 and 216

• 278 and 189

What is the estimated sum of 427 and 618?

From the choices below, which is the correct estimated sum for 745 and 268?

• 950

• 900

• 1 000

• 1 100

In adding numbers mentally, what number should we add to 345 to make it 500?

• 150

• 155

• 100

• 255

In adding numbers using the split method, what number should be written inside the box?

• 20

• 50

• 30

• 70

Add the numbers 303 + 200 + 402.

• 900

• 904

• 805

• 905

Mrs. Torres bought 1 820 pencils for her pupils last 2019. Last year, she also bought 1 932 pencils for her advisory. About how many pencils did she buy for her pupils in the last two years all in all?

• 3 500

• 4 000

• 4 500

• 3 000

What do you need to do when you are estimating to solve a problem?

• Just guess

• Close your eyes and pick a random answer

• Just add or subtract the numbers like normal

• Round the numbers before adding or subtraction