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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 141 · 40 questions
TalentJR

How to do it in your head (Guess, divide, average): Division: round the divisor to the nearest ten and find the closest multiple of it. Square root: guess the nearest whole root, then divide the number by your guess. Average the guess and the answer of the division, and round to 1 decimal place.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 651 ÷ 48? (a) 1300 (b) 130 (c) 13
  2. 2.Best estimate of 2344 ÷ 88? (a) 2600 (b) 260 (c) 26
  3. 3.√56 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.5 (d) 7.3
  4. 4.Best estimate of 653 ÷ 52? (a) 1300 (b) 13 (c) 130
  5. 5.√65 to 1 decimal place? (a) 8.1 (b) 7.8 (c) 8.0 (d) 7.9
  6. 6.Best estimate of 6343 ÷ 72? (a) 910 (b) 9100 (c) 91
  7. 7.Best estimate of 1692 ÷ 22? (a) 8500 (b) 850 (c) 85
  8. 8.Best estimate of 3453 ÷ 72? (a) 4900 (b) 490 (c) 49
  9. 9.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.1 (d) 5.2
  10. 10.Best estimate of 4316 ÷ 54? (a) 8600 (b) 86 (c) 860
  11. 11.Best estimate of 1362 ÷ 76? (a) 1700 (b) 17 (c) 170
  12. 12.Best estimate of 2279 ÷ 78? (a) 2800 (b) 28 (c) 280
  13. 13.Best estimate of 2422 ÷ 66? (a) 3500 (b) 35 (c) 350
  14. 14.Best estimate of 643 ÷ 33? (a) 2100 (b) 210 (c) 21
  15. 15.√98 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 10.1 (d) 10.2
  16. 16.√42 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.4 (d) 6.5
  17. 17.Best estimate of 3820 ÷ 57? (a) 6400 (b) 64 (c) 640
  18. 18.Best estimate of 2081 ÷ 52? (a) 420 (b) 42 (c) 4200
  19. 19.Best estimate of 3631 ÷ 49? (a) 73 (b) 7300 (c) 730
  20. 20.Best estimate of 539 ÷ 34? (a) 180 (b) 18 (c) 1800
  21. 21.Best estimate of 4057 ÷ 72? (a) 5800 (b) 580 (c) 58
  22. 22.√62 to 1 decimal place? (a) 8.2 (b) 8.0 (c) 8.1 (d) 7.9
  23. 23.Best estimate of 1478 ÷ 48? (a) 300 (b) 3000 (c) 30
  24. 24.Best estimate of 1004 ÷ 66? (a) 140 (b) 1400 (c) 14
  25. 25.√55 to 1 decimal place? (a) 7.4 (b) 7.2 (c) 7.1 (d) 7.3
  26. 26.Best estimate of 911 ÷ 56? (a) 1500 (b) 150 (c) 15
  27. 27.Best estimate of 4359 ÷ 83? (a) 5400 (b) 54 (c) 540
  28. 28.√20 to 1 decimal place? (a) 4.2 (b) 4.3 (c) 4.4 (d) 4.5
  29. 29.Best estimate of 4421 ÷ 69? (a) 630 (b) 6300 (c) 63
  30. 30.Best estimate of 1655 ÷ 28? (a) 55 (b) 5500 (c) 550
  31. 31.Best estimate of 2996 ÷ 67? (a) 430 (b) 43 (c) 4300
  32. 32.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.0
  33. 33.Best estimate of 1609 ÷ 72? (a) 2300 (b) 230 (c) 23
  34. 34.Best estimate of 2045 ÷ 71? (a) 290 (b) 29 (c) 2900
  35. 35.Best estimate of 2979 ÷ 34? (a) 9900 (b) 99 (c) 990
  36. 36.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.8 (d) 5.1
  37. 37.Best estimate of 2479 ÷ 71? (a) 35 (b) 3500 (c) 350
  38. 38.√78 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.6 (d) 8.8
  39. 39.Best estimate of 5553 ÷ 82? (a) 690 (b) 6900 (c) 69
  40. 40.Best estimate of 2054 ÷ 58? (a) 34 (b) 340 (c) 3400

Answer key

  1. 13
  2. 26
  3. 7.5
  4. 13
  5. 8.1
  6. 91
  7. 85
  8. 49
  9. 5.4
  10. 86
  11. 17
  12. 28
  13. 35
  14. 21
  15. 9.9
  16. 6.5
  17. 64
  18. 42
  19. 73
  20. 18
  21. 58
  22. 7.9
  23. 30
  24. 14
  25. 7.4
  26. 15
  27. 54
  28. 4.5
  29. 63
  30. 55
  31. 43
  32. 7.3
  33. 23
  34. 29
  35. 99
  36. 5.1
  37. 35
  38. 8.8
  39. 69
  40. 34

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