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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 94 · 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.√46 to 1 decimal place? (a) 6.8 (b) 6.5 (c) 6.7 (d) 6.6
  2. 2.Best estimate of 6030 ÷ 66? (a) 860 (b) 8600 (c) 86
  3. 3.Best estimate of 8122 ÷ 87? (a) 9000 (b) 90 (c) 900
  4. 4.Best estimate of 4332 ÷ 52? (a) 87 (b) 8700 (c) 870
  5. 5.√63 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 7.8 (d) 7.7
  6. 6.Best estimate of 2510 ÷ 73? (a) 3600 (b) 360 (c) 36
  7. 7.Best estimate of 557 ÷ 24? (a) 280 (b) 2800 (c) 28
  8. 8.Best estimate of 6622 ÷ 71? (a) 9500 (b) 95 (c) 950
  9. 9.√26 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.1 (d) 5.0
  10. 10.Best estimate of 2836 ÷ 41? (a) 710 (b) 7100 (c) 71
  11. 11.Best estimate of 2004 ÷ 32? (a) 6700 (b) 67 (c) 670
  12. 12.√69 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.0
  13. 13.Best estimate of 2979 ÷ 67? (a) 4300 (b) 43 (c) 430
  14. 14.√92 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.8 (d) 9.6
  15. 15.√66 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.4 (d) 8.1
  16. 16.√90 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.5
  17. 17.√34 to 1 decimal place? (a) 5.8 (b) 5.7 (c) 6.0 (d) 5.9
  18. 18.√88 to 1 decimal place? (a) 9.7 (b) 9.4 (c) 9.5 (d) 9.6
  19. 19.Best estimate of 2610 ÷ 62? (a) 44 (b) 440 (c) 4400
  20. 20.√55 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  21. 21.Best estimate of 1155 ÷ 46? (a) 230 (b) 23 (c) 2300
  22. 22.Best estimate of 428 ÷ 34? (a) 1400 (b) 14 (c) 140
  23. 23.Best estimate of 1586 ÷ 28? (a) 530 (b) 53 (c) 5300
  24. 24.√77 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.1 (d) 9.0
  25. 25.√56 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.5 (d) 7.6
  26. 26.Best estimate of 499 ÷ 31? (a) 170 (b) 1700 (c) 17
  27. 27.Best estimate of 5378 ÷ 64? (a) 90 (b) 9000 (c) 900
  28. 28.Best estimate of 4442 ÷ 76? (a) 56 (b) 560 (c) 5600
  29. 29.√76 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.7
  30. 30.Best estimate of 2930 ÷ 36? (a) 73 (b) 7300 (c) 730
  31. 31.Best estimate of 1618 ÷ 36? (a) 4000 (b) 40 (c) 400
  32. 32.Best estimate of 5313 ÷ 76? (a) 660 (b) 6600 (c) 66
  33. 33.Best estimate of 1989 ÷ 87? (a) 22 (b) 220 (c) 2200
  34. 34.Best estimate of 681 ÷ 39? (a) 170 (b) 17 (c) 1700
  35. 35.Best estimate of 1930 ÷ 41? (a) 480 (b) 4800 (c) 48
  36. 36.√71 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.5 (d) 8.4
  37. 37.Best estimate of 4684 ÷ 69? (a) 670 (b) 6700 (c) 67
  38. 38.Best estimate of 2402 ÷ 38? (a) 6000 (b) 600 (c) 60
  39. 39.√40 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.4 (d) 6.3
  40. 40.Best estimate of 1163 ÷ 46? (a) 230 (b) 2300 (c) 23

Answer key

  1. 6.8
  2. 86
  3. 90
  4. 87
  5. 7.9
  6. 36
  7. 28
  8. 95
  9. 5.1
  10. 71
  11. 67
  12. 8.3
  13. 43
  14. 9.6
  15. 8.1
  16. 9.5
  17. 5.8
  18. 9.4
  19. 44
  20. 7.4
  21. 23
  22. 14
  23. 53
  24. 8.8
  25. 7.5
  26. 17
  27. 90
  28. 56
  29. 8.7
  30. 73
  31. 40
  32. 66
  33. 22
  34. 17
  35. 48
  36. 8.4
  37. 67
  38. 60
  39. 6.3
  40. 23

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