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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 408 · 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 3300 ÷ 38? (a) 8300 (b) 830 (c) 83
  2. 2.√35 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.2 (d) 6.0
  3. 3.Best estimate of 5263 ÷ 77? (a) 6600 (b) 66 (c) 660
  4. 4.√46 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.8 (d) 6.6
  5. 5.√42 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.4 (d) 6.6
  6. 6.√55 to 1 decimal place? (a) 7.6 (b) 7.7 (c) 7.5 (d) 7.4
  7. 7.Best estimate of 1583 ÷ 28? (a) 530 (b) 53 (c) 5300
  8. 8.√58 to 1 decimal place? (a) 7.7 (b) 7.8 (c) 7.6 (d) 7.9
  9. 9.√38 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.1 (d) 6.4
  10. 10.Best estimate of 1775 ÷ 34? (a) 590 (b) 59 (c) 5900
  11. 11.Best estimate of 3452 ÷ 88? (a) 38 (b) 380 (c) 3800
  12. 12.Best estimate of 2278 ÷ 34? (a) 7600 (b) 76 (c) 760
  13. 13.√84 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.3 (d) 9.1
  14. 14.Best estimate of 3438 ÷ 39? (a) 860 (b) 8600 (c) 86
  15. 15.Best estimate of 2311 ÷ 62? (a) 390 (b) 3900 (c) 39
  16. 16.Best estimate of 7058 ÷ 83? (a) 88 (b) 880 (c) 8800
  17. 17.Best estimate of 426 ÷ 23? (a) 2100 (b) 210 (c) 21
  18. 18.Best estimate of 2759 ÷ 48? (a) 55 (b) 5500 (c) 550
  19. 19.Best estimate of 552 ÷ 43? (a) 1400 (b) 140 (c) 14
  20. 20.Best estimate of 539 ÷ 26? (a) 18 (b) 1800 (c) 180
  21. 21.Best estimate of 1234 ÷ 46? (a) 25 (b) 2500 (c) 250
  22. 22.Best estimate of 7592 ÷ 89? (a) 8400 (b) 840 (c) 84
  23. 23.√32 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.9 (d) 5.8
  24. 24.√94 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 10.0 (d) 9.7
  25. 25.Best estimate of 5911 ÷ 86? (a) 66 (b) 660 (c) 6600
  26. 26.√20 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.4 (d) 4.5
  27. 27.Best estimate of 596 ÷ 37? (a) 15 (b) 150 (c) 1500
  28. 28.Best estimate of 522 ÷ 26? (a) 170 (b) 17 (c) 1700
  29. 29.Best estimate of 3977 ÷ 43? (a) 99 (b) 9900 (c) 990
  30. 30.Best estimate of 953 ÷ 71? (a) 140 (b) 1400 (c) 14
  31. 31.√52 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.1 (d) 7.0
  32. 32.√43 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.6 (d) 6.8
  33. 33.√80 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 9.0
  34. 34.√87 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.4 (d) 9.3
  35. 35.Best estimate of 6597 ÷ 77? (a) 8200 (b) 820 (c) 82
  36. 36.Best estimate of 916 ÷ 43? (a) 23 (b) 230 (c) 2300
  37. 37.Best estimate of 4548 ÷ 52? (a) 910 (b) 91 (c) 9100
  38. 38.Best estimate of 2023 ÷ 52? (a) 40 (b) 400 (c) 4000
  39. 39.Best estimate of 3346 ÷ 53? (a) 67 (b) 6700 (c) 670
  40. 40.√37 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2

Answer key

  1. 83
  2. 5.9
  3. 66
  4. 6.8
  5. 6.5
  6. 7.4
  7. 53
  8. 7.6
  9. 6.2
  10. 59
  11. 38
  12. 76
  13. 9.2
  14. 86
  15. 39
  16. 88
  17. 21
  18. 55
  19. 14
  20. 18
  21. 25
  22. 84
  23. 5.7
  24. 9.7
  25. 66
  26. 4.5
  27. 15
  28. 17
  29. 99
  30. 14
  31. 7.2
  32. 6.6
  33. 8.9
  34. 9.3
  35. 82
  36. 23
  37. 91
  38. 40
  39. 67
  40. 6.1

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