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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 349 · 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.√34 to 1 decimal place? (a) 6.0 (b) 5.7 (c) 5.8 (d) 5.9
  2. 2.Best estimate of 1416 ÷ 42? (a) 35 (b) 350 (c) 3500
  3. 3.Best estimate of 4218 ÷ 82? (a) 530 (b) 5300 (c) 53
  4. 4.Best estimate of 4382 ÷ 63? (a) 730 (b) 73 (c) 7300
  5. 5.√29 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.6 (d) 5.5
  6. 6.√80 to 1 decimal place? (a) 9.0 (b) 9.1 (c) 9.2 (d) 8.9
  7. 7.Best estimate of 2354 ÷ 61? (a) 39 (b) 390 (c) 3900
  8. 8.Best estimate of 4422 ÷ 77? (a) 55 (b) 5500 (c) 550
  9. 9.Best estimate of 3382 ÷ 62? (a) 560 (b) 56 (c) 5600
  10. 10.√23 to 1 decimal place? (a) 5.1 (b) 4.9 (c) 5.0 (d) 4.8
  11. 11.Best estimate of 933 ÷ 76? (a) 1200 (b) 12 (c) 120
  12. 12.Best estimate of 1992 ÷ 62? (a) 330 (b) 3300 (c) 33
  13. 13.√20 to 1 decimal place? (a) 4.2 (b) 4.3 (c) 4.4 (d) 4.5
  14. 14.Best estimate of 1395 ÷ 34? (a) 47 (b) 4700 (c) 470
  15. 15.Best estimate of 1656 ÷ 29? (a) 55 (b) 5500 (c) 550
  16. 16.Best estimate of 3282 ÷ 57? (a) 55 (b) 550 (c) 5500
  17. 17.√89 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  18. 18.√50 to 1 decimal place? (a) 7.2 (b) 6.9 (c) 7.0 (d) 7.1
  19. 19.√74 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.8
  20. 20.√96 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  21. 21.√94 to 1 decimal place? (a) 9.9 (b) 9.7 (c) 9.6 (d) 9.8
  22. 22.√26 to 1 decimal place? (a) 4.8 (b) 5.0 (c) 5.1 (d) 4.9
  23. 23.√92 to 1 decimal place? (a) 9.6 (b) 9.5 (c) 9.7 (d) 9.8
  24. 24.Best estimate of 2583 ÷ 44? (a) 65 (b) 6500 (c) 650
  25. 25.Best estimate of 4791 ÷ 78? (a) 60 (b) 600 (c) 6000
  26. 26.Best estimate of 2423 ÷ 54? (a) 480 (b) 48 (c) 4800
  27. 27.Best estimate of 4612 ÷ 69? (a) 6600 (b) 66 (c) 660
  28. 28.Best estimate of 4018 ÷ 48? (a) 80 (b) 800 (c) 8000
  29. 29.Best estimate of 1352 ÷ 46? (a) 270 (b) 2700 (c) 27
  30. 30.√51 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 7.2
  31. 31.Best estimate of 1962 ÷ 73? (a) 28 (b) 2800 (c) 280
  32. 32.Best estimate of 1216 ÷ 33? (a) 4100 (b) 410 (c) 41
  33. 33.Best estimate of 6498 ÷ 71? (a) 93 (b) 930 (c) 9300
  34. 34.√58 to 1 decimal place? (a) 7.6 (b) 7.9 (c) 7.7 (d) 7.8
  35. 35.Best estimate of 3063 ÷ 44? (a) 770 (b) 77 (c) 7700
  36. 36.Best estimate of 2709 ÷ 52? (a) 540 (b) 54 (c) 5400
  37. 37.Best estimate of 6427 ÷ 81? (a) 8000 (b) 80 (c) 800
  38. 38.Best estimate of 4711 ÷ 54? (a) 940 (b) 94 (c) 9400
  39. 39.Best estimate of 4545 ÷ 62? (a) 76 (b) 760 (c) 7600
  40. 40.Best estimate of 3521 ÷ 84? (a) 4400 (b) 44 (c) 440

Answer key

  1. 5.8
  2. 35
  3. 53
  4. 73
  5. 5.4
  6. 8.9
  7. 39
  8. 55
  9. 56
  10. 4.8
  11. 12
  12. 33
  13. 4.5
  14. 47
  15. 55
  16. 55
  17. 9.4
  18. 7.1
  19. 8.6
  20. 9.8
  21. 9.7
  22. 5.1
  23. 9.6
  24. 65
  25. 60
  26. 48
  27. 66
  28. 80
  29. 27
  30. 7.1
  31. 28
  32. 41
  33. 93
  34. 7.6
  35. 77
  36. 54
  37. 80
  38. 94
  39. 76
  40. 44

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