Estimate to the nearest ten

key notes:

Understanding Estimation

  • Estimation means finding a number close to the actual value.
  • It helps in quick calculations without exact answers.

What is Rounding?

  • Rounding is a method used to estimate numbers to the nearest ten.
  • It makes numbers simpler while keeping them close to the original value.

Steps to Round to the Nearest Ten

Look at the Ones Place: Identify the digit in the ones place of the number.

Apply the Rounding Rule:

  • If the ones digit is 0, 1, 2, 3, or 4, round down to the previous ten.
  • If the ones digit is 5, 6, 7, 8, or 9, round up to the next ten.

Examples

  • 23 → Look at 3 (ones place) → Round down to 20.
  • 37 → Look at 7 (ones place) → Round up to 40.
  • 45 → Look at 5 (ones place) → Round up to 50.

Using Number Lines

  • A number line helps visualize rounding.
  • Find the nearest tens (before and after the number) and check which one is closer.

Real-Life Applications

  • Estimating money (e.g., rounding prices in a store).
  • Estimating distances or quantities quickly.

Learn with an example

✈️ How many marbles are there? Estimate.

  • about 40
  • about 70
  • This is a group of ten marbles:
  • There are not enough marbles to make 7 groups of 10. There are fewer than 70 marbles. There are about 40 marbles.

✈️ How many marbles are there? Estimate.

  • about 30
  • about 60
  • This is a group of ten marbles:
  • There are more than 3 groups of 10 marbles. There are more than 30 marbles. There are about 60 marbles.

✈️ How many marbles are there? Estimate.

  • about 30
  • about 80
  • This is a group of ten marbles:
  • There are not enough marbles to make 8 groups of 10. There are fewer than 80 marbles. There are about 30 marbles.

Let’s practice!🖊️