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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 995 · 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 997 ÷ 29? (a) 33 (b) 330 (c) 3300
  2. 2.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  3. 3.Best estimate of 2628 ÷ 77? (a) 33 (b) 3300 (c) 330
  4. 4.Best estimate of 2781 ÷ 37? (a) 700 (b) 70 (c) 7000
  5. 5.√31 to 1 decimal place? (a) 5.6 (b) 5.9 (c) 5.8 (d) 5.7
  6. 6.Best estimate of 2499 ÷ 42? (a) 6200 (b) 620 (c) 62
  7. 7.√34 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.8 (d) 5.9
  8. 8.Best estimate of 5728 ÷ 67? (a) 820 (b) 82 (c) 8200
  9. 9.√45 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.7
  10. 10.Best estimate of 2539 ÷ 43? (a) 6300 (b) 63 (c) 630
  11. 11.√47 to 1 decimal place? (a) 6.8 (b) 6.7 (c) 6.9 (d) 7.0
  12. 12.√20 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  13. 13.Best estimate of 2647 ÷ 29? (a) 880 (b) 88 (c) 8800
  14. 14.Best estimate of 1079 ÷ 31? (a) 36 (b) 3600 (c) 360
  15. 15.Best estimate of 3752 ÷ 57? (a) 630 (b) 63 (c) 6300
  16. 16.√43 to 1 decimal place? (a) 6.5 (b) 6.6 (c) 6.3 (d) 6.4
  17. 17.Best estimate of 3481 ÷ 43? (a) 87 (b) 870 (c) 8700
  18. 18.Best estimate of 6919 ÷ 87? (a) 77 (b) 7700 (c) 770
  19. 19.√83 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.0 (d) 9.1
  20. 20.Best estimate of 3755 ÷ 86? (a) 4200 (b) 42 (c) 420
  21. 21.Best estimate of 5697 ÷ 67? (a) 810 (b) 8100 (c) 81
  22. 22.Best estimate of 4580 ÷ 69? (a) 6500 (b) 650 (c) 65
  23. 23.Best estimate of 2735 ÷ 43? (a) 68 (b) 6800 (c) 680
  24. 24.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.6 (d) 9.9
  25. 25.Best estimate of 1411 ÷ 27? (a) 470 (b) 4700 (c) 47
  26. 26.Best estimate of 3848 ÷ 76? (a) 4800 (b) 48 (c) 480
  27. 27.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.9 (d) 8.6
  28. 28.Best estimate of 506 ÷ 24? (a) 250 (b) 25 (c) 2500
  29. 29.Best estimate of 524 ÷ 27? (a) 17 (b) 1700 (c) 170
  30. 30.√96 to 1 decimal place? (a) 9.8 (b) 9.9 (c) 10.0 (d) 10.1
  31. 31.√80 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  32. 32.√44 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.7 (d) 6.5
  33. 33.Best estimate of 521 ÷ 42? (a) 130 (b) 1300 (c) 13
  34. 34.√78 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  35. 35.Best estimate of 1099 ÷ 26? (a) 3700 (b) 37 (c) 370
  36. 36.Best estimate of 420 ÷ 26? (a) 1400 (b) 140 (c) 14
  37. 37.Best estimate of 3627 ÷ 38? (a) 9100 (b) 910 (c) 91
  38. 38.Best estimate of 5821 ÷ 79? (a) 73 (b) 730 (c) 7300
  39. 39.Best estimate of 1671 ÷ 76? (a) 21 (b) 210 (c) 2100
  40. 40.Best estimate of 1472 ÷ 74? (a) 210 (b) 21 (c) 2100

Answer key

  1. 33
  2. 9.9
  3. 33
  4. 70
  5. 5.6
  6. 62
  7. 5.8
  8. 82
  9. 6.7
  10. 63
  11. 6.9
  12. 4.5
  13. 88
  14. 36
  15. 63
  16. 6.6
  17. 87
  18. 77
  19. 9.1
  20. 42
  21. 81
  22. 65
  23. 68
  24. 9.7
  25. 47
  26. 48
  27. 8.6
  28. 25
  29. 17
  30. 9.8
  31. 8.9
  32. 6.6
  33. 13
  34. 8.8
  35. 37
  36. 14
  37. 91
  38. 73
  39. 21
  40. 21

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