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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 389 · 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.√47 to 1 decimal place? (a) 7.1 (b) 7.2 (c) 7.0 (d) 6.9
  2. 2.√40 to 1 decimal place? (a) 6.0 (b) 6.2 (c) 6.1 (d) 6.3
  3. 3.Best estimate of 2742 ÷ 49? (a) 55 (b) 550 (c) 5500
  4. 4.Best estimate of 3793 ÷ 71? (a) 54 (b) 5400 (c) 540
  5. 5.Best estimate of 2387 ÷ 83? (a) 3000 (b) 30 (c) 300
  6. 6.Best estimate of 3511 ÷ 79? (a) 440 (b) 4400 (c) 44
  7. 7.√94 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.9
  8. 8.Best estimate of 3143 ÷ 76? (a) 390 (b) 3900 (c) 39
  9. 9.Best estimate of 1749 ÷ 26? (a) 580 (b) 58 (c) 5800
  10. 10.√72 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.4 (d) 8.6
  11. 11.√43 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.7 (d) 6.5
  12. 12.√98 to 1 decimal place? (a) 10.0 (b) 9.7 (c) 9.8 (d) 9.9
  13. 13.Best estimate of 825 ÷ 37? (a) 210 (b) 2100 (c) 21
  14. 14.Best estimate of 3204 ÷ 63? (a) 5300 (b) 53 (c) 530
  15. 15.Best estimate of 737 ÷ 27? (a) 2500 (b) 250 (c) 25
  16. 16.Best estimate of 2583 ÷ 36? (a) 65 (b) 650 (c) 6500
  17. 17.Best estimate of 3155 ÷ 43? (a) 790 (b) 79 (c) 7900
  18. 18.√27 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.1 (d) 5.3
  19. 19.√59 to 1 decimal place? (a) 7.7 (b) 8.0 (c) 7.8 (d) 7.9
  20. 20.Best estimate of 975 ÷ 41? (a) 2400 (b) 240 (c) 24
  21. 21.√41 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.4 (d) 6.3
  22. 22.√96 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.9 (d) 10.1
  23. 23.Best estimate of 2394 ÷ 72? (a) 3400 (b) 340 (c) 34
  24. 24.Best estimate of 1504 ÷ 68? (a) 21 (b) 2100 (c) 210
  25. 25.√74 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  26. 26.√86 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.2 (d) 9.4
  27. 27.√37 to 1 decimal place? (a) 6.3 (b) 6.0 (c) 6.1 (d) 6.2
  28. 28.Best estimate of 713 ÷ 31? (a) 24 (b) 2400 (c) 240
  29. 29.Best estimate of 5106 ÷ 54? (a) 10200 (b) 102 (c) 1020
  30. 30.√22 to 1 decimal place? (a) 4.9 (b) 4.8 (c) 4.7 (d) 5.0
  31. 31.Best estimate of 1022 ÷ 32? (a) 34 (b) 340 (c) 3400
  32. 32.Best estimate of 2063 ÷ 86? (a) 2300 (b) 230 (c) 23
  33. 33.Best estimate of 4395 ÷ 73? (a) 630 (b) 63 (c) 6300
  34. 34.Best estimate of 3275 ÷ 59? (a) 55 (b) 5500 (c) 550
  35. 35.√89 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.6 (d) 9.4
  36. 36.Best estimate of 813 ÷ 26? (a) 27 (b) 2700 (c) 270
  37. 37.Best estimate of 2537 ÷ 38? (a) 63 (b) 630 (c) 6300
  38. 38.Best estimate of 1247 ÷ 51? (a) 2500 (b) 25 (c) 250
  39. 39.√24 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 4.8
  40. 40.√92 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.3 (d) 9.6

Answer key

  1. 6.9
  2. 6.3
  3. 55
  4. 54
  5. 30
  6. 44
  7. 9.7
  8. 39
  9. 58
  10. 8.5
  11. 6.6
  12. 9.9
  13. 21
  14. 53
  15. 25
  16. 65
  17. 79
  18. 5.2
  19. 7.7
  20. 24
  21. 6.4
  22. 9.8
  23. 34
  24. 21
  25. 8.6
  26. 9.3
  27. 6.1
  28. 24
  29. 102
  30. 4.7
  31. 34
  32. 23
  33. 63
  34. 55
  35. 9.4
  36. 27
  37. 63
  38. 25
  39. 4.9
  40. 9.6

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