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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 953 · 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.√20 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.5 (d) 4.4
  2. 2.Best estimate of 3538 ÷ 58? (a) 5900 (b) 59 (c) 590
  3. 3.√92 to 1 decimal place? (a) 9.5 (b) 9.6 (c) 9.7 (d) 9.4
  4. 4.Best estimate of 1365 ÷ 27? (a) 460 (b) 46 (c) 4600
  5. 5.Best estimate of 921 ÷ 56? (a) 150 (b) 15 (c) 1500
  6. 6.Best estimate of 3374 ÷ 39? (a) 8400 (b) 840 (c) 84
  7. 7.Best estimate of 2071 ÷ 23? (a) 1040 (b) 104 (c) 10400
  8. 8.Best estimate of 1476 ÷ 36? (a) 370 (b) 3700 (c) 37
  9. 9.√96 to 1 decimal place? (a) 10.1 (b) 9.9 (c) 10.0 (d) 9.8
  10. 10.√59 to 1 decimal place? (a) 7.9 (b) 7.7 (c) 7.8 (d) 8.0
  11. 11.√89 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.1 (d) 9.2
  12. 12.√62 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.7 (d) 7.9
  13. 13.Best estimate of 3622 ÷ 72? (a) 520 (b) 52 (c) 5200
  14. 14.Best estimate of 3070 ÷ 36? (a) 7700 (b) 770 (c) 77
  15. 15.Best estimate of 1920 ÷ 29? (a) 64 (b) 6400 (c) 640
  16. 16.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  17. 17.Best estimate of 2393 ÷ 57? (a) 4000 (b) 400 (c) 40
  18. 18.√46 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.6 (d) 6.7
  19. 19.Best estimate of 543 ÷ 38? (a) 140 (b) 1400 (c) 14
  20. 20.√69 to 1 decimal place? (a) 8.3 (b) 8.0 (c) 8.1 (d) 8.2
  21. 21.Best estimate of 5369 ÷ 63? (a) 8900 (b) 890 (c) 89
  22. 22.√44 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.5 (d) 6.6
  23. 23.√43 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.9
  24. 24.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 10.0
  25. 25.Best estimate of 1381 ÷ 51? (a) 28 (b) 2800 (c) 280
  26. 26.Best estimate of 2356 ÷ 66? (a) 3400 (b) 34 (c) 340
  27. 27.Best estimate of 1203 ÷ 29? (a) 4000 (b) 400 (c) 40
  28. 28.Best estimate of 3101 ÷ 39? (a) 78 (b) 7800 (c) 780
  29. 29.Best estimate of 324 ÷ 26? (a) 1100 (b) 110 (c) 11
  30. 30.√42 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.6 (d) 6.8
  31. 31.Best estimate of 4312 ÷ 51? (a) 860 (b) 86 (c) 8600
  32. 32.√77 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.8 (d) 8.5
  33. 33.√38 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.1 (d) 6.2
  34. 34.Best estimate of 4052 ÷ 71? (a) 58 (b) 580 (c) 5800
  35. 35.Best estimate of 1537 ÷ 26? (a) 510 (b) 5100 (c) 51
  36. 36.√47 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.8 (d) 6.9
  37. 37.√27 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.3 (d) 5.1
  38. 38.√82 to 1 decimal place? (a) 9.0 (b) 8.9 (c) 9.1 (d) 8.8
  39. 39.Best estimate of 5912 ÷ 88? (a) 66 (b) 6600 (c) 660
  40. 40.Best estimate of 1132 ÷ 82? (a) 14 (b) 1400 (c) 140

Answer key

  1. 4.5
  2. 59
  3. 9.6
  4. 46
  5. 15
  6. 84
  7. 104
  8. 37
  9. 9.8
  10. 7.7
  11. 9.4
  12. 7.9
  13. 52
  14. 77
  15. 64
  16. 5.1
  17. 40
  18. 6.8
  19. 14
  20. 8.3
  21. 89
  22. 6.6
  23. 6.6
  24. 9.7
  25. 28
  26. 34
  27. 40
  28. 78
  29. 11
  30. 6.5
  31. 86
  32. 8.8
  33. 6.2
  34. 58
  35. 51
  36. 6.9
  37. 5.2
  38. 9.1
  39. 66
  40. 14

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