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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 805 · 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.√80 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 9.0 (d) 8.9
  2. 2.Best estimate of 4529 ÷ 52? (a) 9100 (b) 91 (c) 910
  3. 3.Best estimate of 1207 ÷ 26? (a) 4000 (b) 400 (c) 40
  4. 4.Best estimate of 5803 ÷ 88? (a) 6400 (b) 64 (c) 640
  5. 5.Best estimate of 4321 ÷ 52? (a) 8600 (b) 86 (c) 860
  6. 6.√66 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 7.9 (d) 8.1
  7. 7.Best estimate of 2946 ÷ 82? (a) 3700 (b) 370 (c) 37
  8. 8.√32 to 1 decimal place? (a) 5.9 (b) 5.7 (c) 6.0 (d) 5.8
  9. 9.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.0 (d) 4.9
  10. 10.√40 to 1 decimal place? (a) 6.0 (b) 6.3 (c) 6.2 (d) 6.1
  11. 11.√75 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  12. 12.√50 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 7.3
  13. 13.Best estimate of 3447 ÷ 53? (a) 69 (b) 690 (c) 6900
  14. 14.Best estimate of 2823 ÷ 37? (a) 71 (b) 7100 (c) 710
  15. 15.Best estimate of 1364 ÷ 57? (a) 2300 (b) 230 (c) 23
  16. 16.√46 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.5 (d) 6.7
  17. 17.Best estimate of 6417 ÷ 72? (a) 920 (b) 9200 (c) 92
  18. 18.√98 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  19. 19.√27 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.1 (d) 4.9
  20. 20.√96 to 1 decimal place? (a) 10.1 (b) 10.0 (c) 9.9 (d) 9.8
  21. 21.Best estimate of 2646 ÷ 28? (a) 8800 (b) 880 (c) 88
  22. 22.Best estimate of 2862 ÷ 74? (a) 410 (b) 4100 (c) 41
  23. 23.√37 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 5.8
  24. 24.Best estimate of 1023 ÷ 27? (a) 340 (b) 3400 (c) 34
  25. 25.Best estimate of 5689 ÷ 86? (a) 630 (b) 63 (c) 6300
  26. 26.Best estimate of 2669 ÷ 52? (a) 530 (b) 5300 (c) 53
  27. 27.Best estimate of 1076 ÷ 32? (a) 36 (b) 360 (c) 3600
  28. 28.Best estimate of 1360 ÷ 82? (a) 1700 (b) 17 (c) 170
  29. 29.√86 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 9.3
  30. 30.√89 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.4 (d) 9.7
  31. 31.Best estimate of 2098 ÷ 61? (a) 35 (b) 3500 (c) 350
  32. 32.Best estimate of 7819 ÷ 88? (a) 870 (b) 8700 (c) 87
  33. 33.Best estimate of 3194 ÷ 56? (a) 530 (b) 53 (c) 5300
  34. 34.Best estimate of 4311 ÷ 89? (a) 480 (b) 4800 (c) 48
  35. 35.√20 to 1 decimal place? (a) 4.7 (b) 4.5 (c) 4.8 (d) 4.6
  36. 36.Best estimate of 5132 ÷ 57? (a) 8600 (b) 860 (c) 86
  37. 37.√34 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 5.8 (d) 6.1
  38. 38.Best estimate of 6394 ÷ 86? (a) 71 (b) 710 (c) 7100
  39. 39.Best estimate of 550 ÷ 24? (a) 2800 (b) 280 (c) 28
  40. 40.Best estimate of 2690 ÷ 48? (a) 540 (b) 5400 (c) 54

Answer key

  1. 8.9
  2. 91
  3. 40
  4. 64
  5. 86
  6. 8.1
  7. 37
  8. 5.7
  9. 5.1
  10. 6.3
  11. 8.7
  12. 7.1
  13. 69
  14. 71
  15. 23
  16. 6.8
  17. 92
  18. 9.9
  19. 5.2
  20. 9.8
  21. 88
  22. 41
  23. 6.1
  24. 34
  25. 63
  26. 53
  27. 36
  28. 17
  29. 9.3
  30. 9.4
  31. 35
  32. 87
  33. 53
  34. 48
  35. 4.5
  36. 86
  37. 5.8
  38. 71
  39. 28
  40. 54

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