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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 660 · 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 7626 ÷ 82? (a) 950 (b) 9500 (c) 95
  2. 2.√94 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 9.7 (d) 10.0
  3. 3.Best estimate of 1938 ÷ 43? (a) 48 (b) 4800 (c) 480
  4. 4.Best estimate of 1868 ÷ 52? (a) 37 (b) 370 (c) 3700
  5. 5.Best estimate of 1239 ÷ 34? (a) 410 (b) 4100 (c) 41
  6. 6.√37 to 1 decimal place? (a) 6.0 (b) 5.9 (c) 6.1 (d) 6.2
  7. 7.√77 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.9 (d) 8.8
  8. 8.Best estimate of 2633 ÷ 33? (a) 88 (b) 8800 (c) 880
  9. 9.√96 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.5
  10. 10.Best estimate of 1065 ÷ 39? (a) 27 (b) 2700 (c) 270
  11. 11.√47 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.7 (d) 6.8
  12. 12.Best estimate of 1607 ÷ 48? (a) 3200 (b) 32 (c) 320
  13. 13.Best estimate of 3829 ÷ 87? (a) 43 (b) 4300 (c) 430
  14. 14.Best estimate of 1555 ÷ 66? (a) 2200 (b) 220 (c) 22
  15. 15.Best estimate of 4145 ÷ 66? (a) 59 (b) 590 (c) 5900
  16. 16.√72 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.5 (d) 8.2
  17. 17.√46 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 6.8 (d) 7.0
  18. 18.Best estimate of 7536 ÷ 79? (a) 94 (b) 940 (c) 9400
  19. 19.Best estimate of 3243 ÷ 87? (a) 3600 (b) 360 (c) 36
  20. 20.√45 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  21. 21.Best estimate of 1693 ÷ 26? (a) 56 (b) 5600 (c) 560
  22. 22.Best estimate of 2197 ÷ 33? (a) 730 (b) 7300 (c) 73
  23. 23.Best estimate of 2605 ÷ 86? (a) 290 (b) 2900 (c) 29
  24. 24.√21 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.8 (d) 4.6
  25. 25.√22 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 4.6
  26. 26.Best estimate of 4562 ÷ 57? (a) 760 (b) 7600 (c) 76
  27. 27.√90 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.8
  28. 28.Best estimate of 2067 ÷ 34? (a) 69 (b) 6900 (c) 690
  29. 29.Best estimate of 1283 ÷ 83? (a) 1600 (b) 16 (c) 160
  30. 30.Best estimate of 1976 ÷ 36? (a) 49 (b) 490 (c) 4900
  31. 31.Best estimate of 6073 ÷ 64? (a) 10100 (b) 1010 (c) 101
  32. 32.√26 to 1 decimal place? (a) 5.3 (b) 5.2 (c) 5.1 (d) 5.4
  33. 33.Best estimate of 4474 ÷ 86? (a) 500 (b) 50 (c) 5000
  34. 34.Best estimate of 1300 ÷ 48? (a) 2600 (b) 26 (c) 260
  35. 35.Best estimate of 1280 ÷ 36? (a) 3200 (b) 320 (c) 32
  36. 36.√24 to 1 decimal place? (a) 4.9 (b) 5.0 (c) 4.7 (d) 4.8
  37. 37.Best estimate of 3739 ÷ 56? (a) 6200 (b) 62 (c) 620
  38. 38.Best estimate of 3240 ÷ 56? (a) 540 (b) 5400 (c) 54
  39. 39.Best estimate of 583 ÷ 27? (a) 1900 (b) 190 (c) 19
  40. 40.Best estimate of 3186 ÷ 38? (a) 8000 (b) 800 (c) 80

Answer key

  1. 95
  2. 9.7
  3. 48
  4. 37
  5. 41
  6. 6.1
  7. 8.8
  8. 88
  9. 9.8
  10. 27
  11. 6.9
  12. 32
  13. 43
  14. 22
  15. 59
  16. 8.5
  17. 6.8
  18. 94
  19. 36
  20. 6.7
  21. 56
  22. 73
  23. 29
  24. 4.6
  25. 4.7
  26. 76
  27. 9.5
  28. 69
  29. 16
  30. 49
  31. 101
  32. 5.1
  33. 50
  34. 26
  35. 32
  36. 4.9
  37. 62
  38. 54
  39. 19
  40. 80

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