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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 280 · 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.√83 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  2. 2.Best estimate of 1121 ÷ 66? (a) 16 (b) 160 (c) 1600
  3. 3.Best estimate of 2424 ÷ 47? (a) 48 (b) 4800 (c) 480
  4. 4.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.5 (d) 5.8
  5. 5.√43 to 1 decimal place? (a) 6.8 (b) 6.9 (c) 6.7 (d) 6.6
  6. 6.√96 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.7 (d) 9.6
  7. 7.√26 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 5.2 (d) 5.1
  8. 8.√79 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.6 (d) 8.8
  9. 9.Best estimate of 964 ÷ 52? (a) 190 (b) 1900 (c) 19
  10. 10.Best estimate of 2386 ÷ 27? (a) 800 (b) 8000 (c) 80
  11. 11.Best estimate of 4820 ÷ 73? (a) 6900 (b) 690 (c) 69
  12. 12.Best estimate of 2273 ÷ 41? (a) 5700 (b) 570 (c) 57
  13. 13.√23 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  14. 14.Best estimate of 785 ÷ 32? (a) 2600 (b) 260 (c) 26
  15. 15.Best estimate of 1375 ÷ 27? (a) 46 (b) 4600 (c) 460
  16. 16.Best estimate of 859 ÷ 22? (a) 43 (b) 430 (c) 4300
  17. 17.√72 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.2
  18. 18.√44 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.7
  19. 19.Best estimate of 1324 ÷ 54? (a) 26 (b) 260 (c) 2600
  20. 20.√52 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  21. 21.Best estimate of 2021 ÷ 23? (a) 10100 (b) 1010 (c) 101
  22. 22.Best estimate of 4581 ÷ 76? (a) 57 (b) 5700 (c) 570
  23. 23.√48 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.9 (d) 6.7
  24. 24.Best estimate of 1292 ÷ 39? (a) 32 (b) 3200 (c) 320
  25. 25.Best estimate of 592 ÷ 22? (a) 3000 (b) 300 (c) 30
  26. 26.Best estimate of 769 ÷ 27? (a) 26 (b) 2600 (c) 260
  27. 27.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.4
  28. 28.Best estimate of 1709 ÷ 26? (a) 570 (b) 57 (c) 5700
  29. 29.Best estimate of 1687 ÷ 57? (a) 280 (b) 2800 (c) 28
  30. 30.√50 to 1 decimal place? (a) 7.0 (b) 6.9 (c) 7.1 (d) 6.8
  31. 31.Best estimate of 1098 ÷ 33? (a) 370 (b) 3700 (c) 37
  32. 32.Best estimate of 1916 ÷ 79? (a) 240 (b) 2400 (c) 24
  33. 33.√55 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.1 (d) 7.4
  34. 34.Best estimate of 2335 ÷ 41? (a) 580 (b) 58 (c) 5800
  35. 35.√32 to 1 decimal place? (a) 5.7 (b) 5.5 (c) 5.4 (d) 5.6
  36. 36.Best estimate of 3416 ÷ 41? (a) 850 (b) 85 (c) 8500
  37. 37.Best estimate of 1749 ÷ 49? (a) 350 (b) 3500 (c) 35
  38. 38.Best estimate of 2095 ÷ 26? (a) 7000 (b) 70 (c) 700
  39. 39.Best estimate of 6079 ÷ 66? (a) 870 (b) 87 (c) 8700
  40. 40.√56 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.4 (d) 7.5

Answer key

  1. 9.1
  2. 16
  3. 48
  4. 5.8
  5. 6.6
  6. 9.8
  7. 5.1
  8. 8.9
  9. 19
  10. 80
  11. 69
  12. 57
  13. 4.8
  14. 26
  15. 46
  16. 43
  17. 8.5
  18. 6.6
  19. 26
  20. 7.2
  21. 101
  22. 57
  23. 6.9
  24. 32
  25. 30
  26. 26
  27. 9.1
  28. 57
  29. 28
  30. 7.1
  31. 37
  32. 24
  33. 7.4
  34. 58
  35. 5.7
  36. 85
  37. 35
  38. 70
  39. 87
  40. 7.5

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