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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 362 · 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 4546 ÷ 66? (a) 6500 (b) 65 (c) 650
  2. 2.√75 to 1 decimal place? (a) 8.7 (b) 8.4 (c) 8.6 (d) 8.5
  3. 3.Best estimate of 2518 ÷ 46? (a) 50 (b) 5000 (c) 500
  4. 4.Best estimate of 2171 ÷ 36? (a) 540 (b) 5400 (c) 54
  5. 5.Best estimate of 2277 ÷ 38? (a) 57 (b) 570 (c) 5700
  6. 6.√96 to 1 decimal place? (a) 9.8 (b) 10.0 (c) 9.9 (d) 10.1
  7. 7.Best estimate of 487 ÷ 21? (a) 240 (b) 2400 (c) 24
  8. 8.Best estimate of 3375 ÷ 46? (a) 68 (b) 680 (c) 6800
  9. 9.Best estimate of 3350 ÷ 69? (a) 48 (b) 480 (c) 4800
  10. 10.Best estimate of 1154 ÷ 87? (a) 13 (b) 130 (c) 1300
  11. 11.√56 to 1 decimal place? (a) 7.4 (b) 7.5 (c) 7.6 (d) 7.3
  12. 12.Best estimate of 2252 ÷ 39? (a) 56 (b) 560 (c) 5600
  13. 13.Best estimate of 2288 ÷ 61? (a) 38 (b) 3800 (c) 380
  14. 14.Best estimate of 1554 ÷ 82? (a) 190 (b) 1900 (c) 19
  15. 15.Best estimate of 1578 ÷ 32? (a) 530 (b) 53 (c) 5300
  16. 16.Best estimate of 1831 ÷ 46? (a) 370 (b) 3700 (c) 37
  17. 17.Best estimate of 1590 ÷ 26? (a) 53 (b) 5300 (c) 530
  18. 18.Best estimate of 2919 ÷ 31? (a) 970 (b) 97 (c) 9700
  19. 19.√86 to 1 decimal place? (a) 9.3 (b) 9.1 (c) 9.0 (d) 9.2
  20. 20.Best estimate of 2260 ÷ 26? (a) 75 (b) 750 (c) 7500
  21. 21.Best estimate of 1418 ÷ 36? (a) 3500 (b) 35 (c) 350
  22. 22.Best estimate of 5199 ÷ 78? (a) 6500 (b) 65 (c) 650
  23. 23.√42 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.6 (d) 6.5
  24. 24.√89 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  25. 25.Best estimate of 5436 ÷ 79? (a) 6800 (b) 68 (c) 680
  26. 26.Best estimate of 1859 ÷ 62? (a) 31 (b) 3100 (c) 310
  27. 27.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.1
  28. 28.√24 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  29. 29.Best estimate of 2955 ÷ 38? (a) 7400 (b) 740 (c) 74
  30. 30.√90 to 1 decimal place? (a) 9.6 (b) 9.8 (c) 9.7 (d) 9.5
  31. 31.Best estimate of 4889 ÷ 52? (a) 9800 (b) 980 (c) 98
  32. 32.√21 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.9
  33. 33.√76 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  34. 34.√61 to 1 decimal place? (a) 8.0 (b) 7.9 (c) 8.1 (d) 7.8
  35. 35.Best estimate of 1365 ÷ 87? (a) 150 (b) 1500 (c) 15
  36. 36.√65 to 1 decimal place? (a) 8.1 (b) 7.9 (c) 7.8 (d) 8.0
  37. 37.√88 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.1 (d) 9.2
  38. 38.√85 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.2 (d) 9.4
  39. 39.Best estimate of 1437 ÷ 57? (a) 24 (b) 2400 (c) 240
  40. 40.√40 to 1 decimal place? (a) 6.5 (b) 6.3 (c) 6.4 (d) 6.6

Answer key

  1. 65
  2. 8.7
  3. 50
  4. 54
  5. 57
  6. 9.8
  7. 24
  8. 68
  9. 48
  10. 13
  11. 7.5
  12. 56
  13. 38
  14. 19
  15. 53
  16. 37
  17. 53
  18. 97
  19. 9.3
  20. 75
  21. 35
  22. 65
  23. 6.5
  24. 9.4
  25. 68
  26. 31
  27. 6.2
  28. 4.9
  29. 74
  30. 9.5
  31. 98
  32. 4.6
  33. 8.7
  34. 7.8
  35. 15
  36. 8.1
  37. 9.4
  38. 9.2
  39. 24
  40. 6.3

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