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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 941 · 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 661 ÷ 21? (a) 330 (b) 33 (c) 3300
  2. 2.√44 to 1 decimal place? (a) 6.4 (b) 6.7 (c) 6.5 (d) 6.6
  3. 3.Best estimate of 5415 ÷ 67? (a) 770 (b) 77 (c) 7700
  4. 4.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.5
  5. 5.√23 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.8
  6. 6.Best estimate of 6793 ÷ 72? (a) 970 (b) 9700 (c) 97
  7. 7.√92 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  8. 8.√86 to 1 decimal place? (a) 9.6 (b) 9.4 (c) 9.5 (d) 9.3
  9. 9.Best estimate of 5092 ÷ 66? (a) 730 (b) 73 (c) 7300
  10. 10.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 8.7 (d) 8.6
  11. 11.Best estimate of 4651 ÷ 56? (a) 78 (b) 780 (c) 7800
  12. 12.Best estimate of 2304 ÷ 37? (a) 5800 (b) 580 (c) 58
  13. 13.√50 to 1 decimal place? (a) 7.2 (b) 7.1 (c) 7.3 (d) 7.0
  14. 14.Best estimate of 3148 ÷ 88? (a) 350 (b) 35 (c) 3500
  15. 15.Best estimate of 1549 ÷ 69? (a) 220 (b) 22 (c) 2200
  16. 16.√20 to 1 decimal place? (a) 4.8 (b) 4.6 (c) 4.5 (d) 4.7
  17. 17.√75 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.6 (d) 8.7
  18. 18.Best estimate of 4297 ÷ 72? (a) 6100 (b) 610 (c) 61
  19. 19.Best estimate of 2152 ÷ 29? (a) 72 (b) 7200 (c) 720
  20. 20.Best estimate of 4975 ÷ 53? (a) 100 (b) 1000 (c) 10000
  21. 21.√90 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  22. 22.Best estimate of 2030 ÷ 43? (a) 510 (b) 51 (c) 5100
  23. 23.√31 to 1 decimal place? (a) 5.4 (b) 5.5 (c) 5.6 (d) 5.7
  24. 24.√35 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.2 (d) 6.0
  25. 25.√22 to 1 decimal place? (a) 4.8 (b) 4.7 (c) 4.6 (d) 4.5
  26. 26.√67 to 1 decimal place? (a) 8.4 (b) 8.1 (c) 8.3 (d) 8.2
  27. 27.Best estimate of 2876 ÷ 39? (a) 720 (b) 72 (c) 7200
  28. 28.√98 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 9.6
  29. 29.√26 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.1
  30. 30.√88 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  31. 31.√69 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.0 (d) 8.1
  32. 32.Best estimate of 1534 ÷ 86? (a) 1700 (b) 17 (c) 170
  33. 33.Best estimate of 4744 ÷ 66? (a) 6800 (b) 680 (c) 68
  34. 34.Best estimate of 4649 ÷ 62? (a) 7700 (b) 770 (c) 77
  35. 35.Best estimate of 3984 ÷ 72? (a) 570 (b) 57 (c) 5700
  36. 36.Best estimate of 3226 ÷ 38? (a) 81 (b) 810 (c) 8100
  37. 37.Best estimate of 1641 ÷ 28? (a) 550 (b) 55 (c) 5500
  38. 38.√58 to 1 decimal place? (a) 7.8 (b) 7.9 (c) 7.6 (d) 7.7
  39. 39.Best estimate of 2442 ÷ 29? (a) 81 (b) 810 (c) 8100
  40. 40.Best estimate of 1161 ÷ 31? (a) 3900 (b) 390 (c) 39

Answer key

  1. 33
  2. 6.6
  3. 77
  4. 6.6
  5. 4.8
  6. 97
  7. 9.6
  8. 9.3
  9. 73
  10. 8.8
  11. 78
  12. 58
  13. 7.1
  14. 35
  15. 22
  16. 4.5
  17. 8.7
  18. 61
  19. 72
  20. 100
  21. 9.5
  22. 51
  23. 5.6
  24. 5.9
  25. 4.7
  26. 8.2
  27. 72
  28. 9.9
  29. 5.1
  30. 9.4
  31. 8.3
  32. 17
  33. 68
  34. 77
  35. 57
  36. 81
  37. 55
  38. 7.6
  39. 81
  40. 39

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