What is Estimating?

Estimating means making a good guess about a number or amount. It helps us quickly find out how much we think something is without doing all the exact calculations. Estimating is useful for checking our answers or figuring out if a number makes sense in a real-life situation.

Why do We Estimate?

  • Quick Checks: Estimating helps us check if our answers are reasonable.
  • Save Time: It can save time when we need to make quick calculations.
  • Planning: When shopping, it helps us plan our budget by guessing totals.

How to Estimate

Rounding Numbers

One common way to estimate is by rounding numbers. Rounding means changing a number to a nearby, simpler number, making it easier to work with.

Rules for Rounding:

  1. Look at the digit to the right of the place value you want to round to.
  2. If it’s 5 or more, round up.
  3. If it’s 4 or less, round down.

Example:

  • To estimate 47 + 29:
    • Round 47 to 50 (because 7 is 5 or more).
    • Round 29 to 30 (because 9 is 5 or more).
    • Now, calculate: 50 + 30 = 80.
    • So, an estimate for 47 + 29 is 80.

Estimating in Real-Life Situations

When you go shopping, you might want to know how much two items cost together without using a calculator. You can round the prices and add them up!

Example:

  • If a toy costs £14.99 and a book costs £6.49:
    • Round £14.99 to £15.
    • Round £6.49 to £6.
    • Estimate: £15 + £6 = £21.

Tips and Tricks for Estimating

  • Use Friendly Numbers: Round to the nearest 10 or 100, whichever is easier for you.
  • Check Your Work: After calculating, see if your answer is close to what you estimated.
  • Practice: The more you practice estimating, the better you will get!

Questions on Estimating

Easy Level Questions

  1. Estimate 23 + 34.
  2. Estimate 58 – 21.
  3. Estimate 45 + 18.
  4. Estimate 72 – 30.
  5. Estimate 15 x 4.
  6. Estimate 81 ÷ 9.
  7. Estimate 67 + 22.
  8. Estimate 99 – 47.
  9. Estimate 32 + 16.
  10. Estimate 73 x 2.
  11. Estimate 54 ÷ 6.
  12. Estimate 29 + 14.
  13. Estimate 25 – 9.
  14. Estimate 40 + 19.
  15. Estimate 81 – 50.
  16. Estimate 11 x 3.
  17. Estimate 60 ÷ 5.
  18. Estimate 88 + 12.
  19. Estimate 95 – 45.
  20. Estimate 10 x 6.

Medium Level Questions

  1. Estimate 145 + 267.
  2. Estimate 183 – 98.
  3. Estimate 256 + 137.
  4. Estimate 412 – 199.
  5. Estimate 225 x 6.
  6. Estimate 576 ÷ 8.
  7. Estimate 134 + 225.
  8. Estimate 380 – 145.
  9. Estimate 275 + 145.
  10. Estimate 640 ÷ 4.
  11. Estimate 197 + 203.
  12. Estimate 250 – 67.
  13. Estimate 305 x 5.
  14. Estimate 489 ÷ 3.
  15. Estimate 412 + 189.
  16. Estimate 578 – 300.
  17. Estimate 220 + 80.
  18. Estimate 891 – 500.
  19. Estimate 150 x 2.
  20. Estimate 480 ÷ 12.

Hard Level Questions

  1. Estimate 789 + 654.
  2. Estimate 950 – 378.
  3. Estimate 1234 + 567.
  4. Estimate 876 – 459.
  5. Estimate 432 x 24.
  6. Estimate 1024 ÷ 16.
  7. Estimate 678 + 345.
  8. Estimate 999 – 555.
  9. Estimate 430 + 275.
  10. Estimate 888 ÷ 4.
  11. Estimate 564 + 678.
  12. Estimate 842 – 295.
  13. Estimate 320 x 15.
  14. Estimate 1296 ÷ 6.
  15. Estimate 789 + 234.
  16. Estimate 654 – 321.
  17. Estimate 500 x 7.
  18. Estimate 980 ÷ 20.
  19. Estimate 348 + 765.
  20. Estimate 999 – 444.

Answers and Explanations

Easy Level Answers

  1. 23 + 34 → 20 + 30 = 50
  2. 58 – 21 → 60 – 20 = 40
  3. 45 + 18 → 50 + 20 = 70
  4. 72 – 30 → 70 – 30 = 40
  5. 15 x 4 → 20 x 4 = 80
  6. 81 ÷ 9 → 80 ÷ 10 = 8
  7. 67 + 22 → 70 + 20 = 90
  8. 99 – 47 → 100 – 50 = 50
  9. 32 + 16 → 30 + 20 = 50
  10. 73 x 2 → 70 x 2 = 140
  11. 54 ÷ 6 → 50 ÷ 5 = 10
  12. 29 + 14 → 30 + 10 = 40
  13. 25 – 9 → 30 – 10 = 20
  14. 40 + 19 → 40 + 20 = 60
  15. 81 – 50 → 80 – 50 = 30
  16. 11 x 3 → 10 x 3 = 30
  17. 60 ÷ 5 → 60 ÷ 5 = 12
  18. 88 + 12 → 90 + 10 = 100
  19. 95 – 45 → 100 – 50 = 50
  20. 10 x 6 → 10 x 6 = 60

Medium Level Answers

  1. 145 + 267 → 150 + 270 = 420
  2. 183 – 98 → 180 – 100 = 80
  3. 256 + 137 → 260 + 140 = 400
  4. 412 – 199 → 410 – 200 = 210
  5. 225 x 6 → 230 x 6 = 1380
  6. 576 ÷ 8 → 580 ÷ 10 = 58
  7. 134 + 225 → 130 + 230 = 360
  8. 380 – 145 → 380 – 150 = 230
  9. 275 + 145 → 280 + 150 = 430
  10. 640 ÷ 4 → 640 ÷ 4 = 160
  11. 197 + 203 → 200 + 200 = 400
  12. 250 – 67 → 250 – 70 = 180
  13. 305 x 5 → 300 x 5 = 1500
  14. 489 ÷ 3 → 490 ÷ 5 = 100
  15. 412 + 189 → 410 + 190 = 600
  16. 578 – 300 → 580 – 300 = 280
  17. 220 + 80 → 220 + 80 = 300
  18. 891 – 500 → 890 – 500 = 390
  19. 150 x 2 → 150 x 2 = 300
  20. 480 ÷ 12 → 480 ÷ 10 = 48

Hard Level Answers

  1. 789 + 654 → 790 + 650 = 1440
  2. 950 – 378 → 950 – 380 = 570
  3. 1234 + 567 → 1200 + 600 = 1800
  4. 876 – 459 → 880 – 460 = 420
  5. 432 x 24 → 430 x 20 = 8600
  6. 1024 ÷ 16 → 1020 ÷ 20 = 51
  7. 678 + 345 → 680 + 350 = 1030
  8. 999 – 555 → 1000 – 550 = 450
  9. 430 + 275 → 430 + 280 = 710
  10. 888 ÷ 4 → 890 ÷ 4 = 220
  11. 564 + 678 → 560 + 680 = 1240
  12. 842 – 295 → 840 – 300 = 540
  13. 320 x 15 → 300 x 15 = 4500
  14. 1296 ÷ 6 → 1300 ÷ 5 = 260
  15. 789 + 234 → 790 + 230 = 1020
  16. 654 – 321 → 650 – 320 = 330
  17. 500 x 7 → 500 x 7 = 3500
  18. 980 ÷ 20 → 980 ÷ 20 = 49
  19. 348 + 765 → 350 + 770 = 1120
  20. 999 – 444 → 1000 – 450 = 550

Conclusion

Estimating is a helpful skill that allows you to make quick calculations and checks. Practice estimating in different situations, and soon you’ll find it easier to make good guesses about numbers!