Introduction to Rounding

Hello, Year 7! Today, we are going to learn about rounding whole numbers and decimals. Rounding can help us simplify numbers to make them easier to work with. Sometimes, we might even need to find a missing digit in a number after rounding!

What Does Rounding Mean?

Rounding means changing a number to a nearby, simpler number. For example, if we have the number 67, we might round it to 70 because 70 is the nearest ten.

Key Rules for Rounding

  1. Identify the digit to round: Look at the place value you want to round to.
  2. Look at the next digit: If it’s 5 or more, round up. If it’s 4 or less, round down.
  3. Change the following digits to zero: After rounding, all digits to the right of the rounded digit become zero.

Rounding Decimals

When rounding decimals, the same rules apply. For example, if we want to round 3.67 to one decimal place, we look at the second decimal (7). Since 7 is more than 5, we round up. So, 3.67 becomes 3.7.

Finding the Missing Digit

Sometimes, you might encounter a number with a missing digit, like 4?5, and you need to find out what the question mark is when rounding. Here’s how to do it:

  1. Identify the rounded value: Know what number you want to round to.
  2. Use the rounding rules: Check the digit next to the missing digit to determine if you round up or down.
  3. Test possible digits: Substitute numbers 0-9 in place of the missing digit to see which one fits.

Example of Finding the Missing Digit

Let’s say we have the number 4?5 that rounds to 450.

  1. The missing digit is in the tens place.
  2. The digit after it is 5.
  3. Since we are rounding to the nearest ten and the next digit is 5, the missing digit must be 4. So, 445 rounds to 450.

Tips and Tricks

  • Always remember the rounding rules!
  • Write down the number and the place value you are rounding to.
  • Practice makes perfect—try rounding different numbers!

Questions

Easy Level Questions

  1. Round 36 to the nearest ten: 3?
  2. Round 82.4 to one decimal place: 8?.?
  3. Round 15 to the nearest ten: 1?
  4. Round 49.7 to one decimal place: 4?.?
  5. Round 23 to the nearest ten: 2?
  6. Round 56 to the nearest ten: 5?
  7. Round 70.2 to one decimal place: 7?.?
  8. Round 91 to the nearest ten: 9?
  9. Round 15.9 to one decimal place: 1?.?
  10. Round 44 to the nearest ten: 4?

Medium Level Questions

  1. Round 237 to the nearest hundred: 2?
  2. Round 18.3 to one decimal place: 1?.?
  3. Round 67 to the nearest ten: 6?
  4. Round 85.6 to one decimal place: 8?.?
  5. Round 432 to the nearest hundred: 4?
  6. Round 98.4 to one decimal place: 9?.?
  7. Round 59 to the nearest ten: 5?
  8. Round 72.5 to one decimal place: 7?.?
  9. Round 145 to the nearest hundred: 1?
  10. Round 26.8 to one decimal place: 2?.?

Hard Level Questions

  1. Round 563 to the nearest hundred: 5?
  2. Round 84.67 to one decimal place: 8?.?
  3. Round 292 to the nearest hundred: 2?
  4. Round 777.4 to one decimal place: 7?.?
  5. Round 450 to the nearest hundred: 4?
  6. Round 398.5 to one decimal place: 3?.?
  7. Round 812 to the nearest hundred: 8?
  8. Round 67.89 to one decimal place: 6?.?
  9. Round 512 to the nearest hundred: 5?
  10. Round 99.99 to one decimal place: 9?.?

Answers

Easy Level Answers

  1. 3 → 40
  2. 8 → 8.4
  3. 1 → 20
  4. 4 → 50
  5. 2 → 20
  6. 5 → 60
  7. 7 → 70.0
  8. 9 → 90
  9. 1 → 1.9
  10. 4 → 40

Medium Level Answers

  1. 2 → 200
  2. 1 → 18.3
  3. 6 → 70
  4. 8 → 85.6
  5. 4 → 400
  6. 9 → 98.4
  7. 5 → 60
  8. 7 → 73.0
  9. 1 → 100
  10. 2 → 27.0

Hard Level Answers

  1. 5 → 600
  2. 8 → 84.7
  3. 2 → 300
  4. 7 → 777.0
  5. 4 → 500
  6. 3 → 399.0
  7. 8 → 800
  8. 6 → 67.9
  9. 5 → 500
  10. 9 → 100.0

Now, let’s practice these questions! Happy rounding!