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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 65 · 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.√75 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.6 (d) 8.7
  2. 2.√82 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.1 (d) 9.4
  3. 3.Best estimate of 768 ÷ 37? (a) 19 (b) 190 (c) 1900
  4. 4.Best estimate of 2961 ÷ 61? (a) 490 (b) 4900 (c) 49
  5. 5.√31 to 1 decimal place? (a) 5.6 (b) 5.8 (c) 5.9 (d) 5.7
  6. 6.Best estimate of 3170 ÷ 46? (a) 63 (b) 6300 (c) 630
  7. 7.Best estimate of 947 ÷ 36? (a) 2400 (b) 240 (c) 24
  8. 8.√77 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.9 (d) 8.7
  9. 9.Best estimate of 2106 ÷ 87? (a) 23 (b) 2300 (c) 230
  10. 10.√90 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.5 (d) 9.4
  11. 11.Best estimate of 3428 ÷ 54? (a) 69 (b) 690 (c) 6900
  12. 12.Best estimate of 2377 ÷ 81? (a) 3000 (b) 300 (c) 30
  13. 13.Best estimate of 570 ÷ 42? (a) 140 (b) 1400 (c) 14
  14. 14.Best estimate of 1000 ÷ 42? (a) 250 (b) 25 (c) 2500
  15. 15.Best estimate of 2124 ÷ 26? (a) 7100 (b) 710 (c) 71
  16. 16.Best estimate of 6819 ÷ 89? (a) 7600 (b) 76 (c) 760
  17. 17.√46 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.7 (d) 6.6
  18. 18.Best estimate of 3399 ÷ 68? (a) 4900 (b) 49 (c) 490
  19. 19.√58 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.7 (d) 7.5
  20. 20.Best estimate of 4082 ÷ 61? (a) 680 (b) 6800 (c) 68
  21. 21.√42 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  22. 22.Best estimate of 5779 ÷ 76? (a) 72 (b) 7200 (c) 720
  23. 23.Best estimate of 1262 ÷ 82? (a) 1600 (b) 160 (c) 16
  24. 24.Best estimate of 4012 ÷ 59? (a) 67 (b) 670 (c) 6700
  25. 25.√61 to 1 decimal place? (a) 7.8 (b) 8.1 (c) 8.0 (d) 7.9
  26. 26.√26 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.1 (d) 5.3
  27. 27.√38 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.2 (d) 6.5
  28. 28.Best estimate of 748 ÷ 32? (a) 250 (b) 2500 (c) 25
  29. 29.Best estimate of 2288 ÷ 52? (a) 4600 (b) 46 (c) 460
  30. 30.Best estimate of 2200 ÷ 66? (a) 3100 (b) 310 (c) 31
  31. 31.Best estimate of 1312 ÷ 86? (a) 1500 (b) 15 (c) 150
  32. 32.√43 to 1 decimal place? (a) 6.6 (b) 6.9 (c) 6.7 (d) 6.8
  33. 33.Best estimate of 7168 ÷ 86? (a) 80 (b) 800 (c) 8000
  34. 34.Best estimate of 5631 ÷ 63? (a) 94 (b) 940 (c) 9400
  35. 35.√41 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  36. 36.Best estimate of 1507 ÷ 81? (a) 190 (b) 19 (c) 1900
  37. 37.Best estimate of 866 ÷ 22? (a) 4300 (b) 430 (c) 43
  38. 38.√22 to 1 decimal place? (a) 5.0 (b) 4.9 (c) 4.8 (d) 4.7
  39. 39.√40 to 1 decimal place? (a) 6.1 (b) 6.3 (c) 6.4 (d) 6.2
  40. 40.Best estimate of 2474 ÷ 26? (a) 8200 (b) 820 (c) 82

Answer key

  1. 8.7
  2. 9.1
  3. 19
  4. 49
  5. 5.6
  6. 63
  7. 24
  8. 8.8
  9. 23
  10. 9.5
  11. 69
  12. 30
  13. 14
  14. 25
  15. 71
  16. 76
  17. 6.8
  18. 49
  19. 7.6
  20. 68
  21. 6.5
  22. 72
  23. 16
  24. 67
  25. 7.8
  26. 5.1
  27. 6.2
  28. 25
  29. 46
  30. 31
  31. 15
  32. 6.6
  33. 80
  34. 94
  35. 6.4
  36. 19
  37. 43
  38. 4.7
  39. 6.3
  40. 82

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