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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 667 · 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 1393 ÷ 23? (a) 70 (b) 7000 (c) 700
  2. 2.√20 to 1 decimal place? (a) 4.4 (b) 4.3 (c) 4.5 (d) 4.6
  3. 3.Best estimate of 2967 ÷ 37? (a) 740 (b) 74 (c) 7400
  4. 4.√69 to 1 decimal place? (a) 8.2 (b) 8.4 (c) 8.3 (d) 8.5
  5. 5.Best estimate of 3475 ÷ 49? (a) 70 (b) 7000 (c) 700
  6. 6.Best estimate of 2293 ÷ 31? (a) 760 (b) 76 (c) 7600
  7. 7.Best estimate of 1789 ÷ 77? (a) 220 (b) 22 (c) 2200
  8. 8.√37 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 5.9 (d) 6.0
  9. 9.Best estimate of 3647 ÷ 66? (a) 5200 (b) 52 (c) 520
  10. 10.√87 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  11. 11.√30 to 1 decimal place? (a) 5.5 (b) 5.8 (c) 5.7 (d) 5.6
  12. 12.Best estimate of 5754 ÷ 62? (a) 960 (b) 96 (c) 9600
  13. 13.√76 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 8.9 (d) 8.6
  14. 14.Best estimate of 1758 ÷ 52? (a) 3500 (b) 350 (c) 35
  15. 15.√43 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.7 (d) 6.9
  16. 16.Best estimate of 2491 ÷ 77? (a) 31 (b) 310 (c) 3100
  17. 17.Best estimate of 1084 ÷ 66? (a) 150 (b) 1500 (c) 15
  18. 18.Best estimate of 1180 ÷ 23? (a) 5900 (b) 59 (c) 590
  19. 19.Best estimate of 462 ÷ 21? (a) 2300 (b) 230 (c) 23
  20. 20.√65 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.1
  21. 21.Best estimate of 1130 ÷ 24? (a) 57 (b) 570 (c) 5700
  22. 22.Best estimate of 4752 ÷ 81? (a) 59 (b) 590 (c) 5900
  23. 23.√29 to 1 decimal place? (a) 5.4 (b) 5.6 (c) 5.5 (d) 5.7
  24. 24.Best estimate of 1282 ÷ 29? (a) 4300 (b) 430 (c) 43
  25. 25.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 8.9 (d) 9.0
  26. 26.Best estimate of 422 ÷ 29? (a) 1400 (b) 14 (c) 140
  27. 27.√72 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.2
  28. 28.Best estimate of 1805 ÷ 82? (a) 2300 (b) 23 (c) 230
  29. 29.Best estimate of 5967 ÷ 64? (a) 9900 (b) 99 (c) 990
  30. 30.Best estimate of 4400 ÷ 64? (a) 730 (b) 7300 (c) 73
  31. 31.Best estimate of 1178 ÷ 41? (a) 290 (b) 2900 (c) 29
  32. 32.Best estimate of 1525 ÷ 23? (a) 76 (b) 760 (c) 7600
  33. 33.Best estimate of 4853 ÷ 72? (a) 6900 (b) 69 (c) 690
  34. 34.√42 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.3 (d) 6.5
  35. 35.Best estimate of 3685 ÷ 72? (a) 53 (b) 530 (c) 5300
  36. 36.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.4 (d) 8.5
  37. 37.√50 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.0 (d) 7.1
  38. 38.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.8
  39. 39.Best estimate of 2838 ÷ 87? (a) 32 (b) 3200 (c) 320
  40. 40.Best estimate of 2073 ÷ 48? (a) 4100 (b) 410 (c) 41

Answer key

  1. 70
  2. 4.5
  3. 74
  4. 8.3
  5. 70
  6. 76
  7. 22
  8. 6.1
  9. 52
  10. 9.3
  11. 5.5
  12. 96
  13. 8.7
  14. 35
  15. 6.6
  16. 31
  17. 15
  18. 59
  19. 23
  20. 8.1
  21. 57
  22. 59
  23. 5.4
  24. 43
  25. 9.1
  26. 14
  27. 8.5
  28. 23
  29. 99
  30. 73
  31. 29
  32. 76
  33. 69
  34. 6.5
  35. 53
  36. 8.6
  37. 7.1
  38. 5.6
  39. 32
  40. 41

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