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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 902 · 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 2683 ÷ 62? (a) 45 (b) 450 (c) 4500
  2. 2.Best estimate of 2216 ÷ 44? (a) 55 (b) 5500 (c) 550
  3. 3.√63 to 1 decimal place? (a) 8.0 (b) 8.2 (c) 8.1 (d) 7.9
  4. 4.Best estimate of 1997 ÷ 23? (a) 1000 (b) 10000 (c) 100
  5. 5.Best estimate of 644 ÷ 41? (a) 16 (b) 1600 (c) 160
  6. 6.Best estimate of 4696 ÷ 81? (a) 59 (b) 5900 (c) 590
  7. 7.√87 to 1 decimal place? (a) 9.4 (b) 9.6 (c) 9.3 (d) 9.5
  8. 8.Best estimate of 1283 ÷ 86? (a) 14 (b) 1400 (c) 140
  9. 9.Best estimate of 2767 ÷ 52? (a) 5500 (b) 550 (c) 55
  10. 10.√42 to 1 decimal place? (a) 6.7 (b) 6.5 (c) 6.6 (d) 6.4
  11. 11.√27 to 1 decimal place? (a) 5.2 (b) 5.3 (c) 5.1 (d) 5.0
  12. 12.Best estimate of 657 ÷ 21? (a) 330 (b) 3300 (c) 33
  13. 13.√28 to 1 decimal place? (a) 5.4 (b) 5.3 (c) 5.2 (d) 5.1
  14. 14.Best estimate of 5926 ÷ 82? (a) 74 (b) 740 (c) 7400
  15. 15.Best estimate of 1332 ÷ 71? (a) 19 (b) 1900 (c) 190
  16. 16.√34 to 1 decimal place? (a) 5.8 (b) 5.9 (c) 6.1 (d) 6.0
  17. 17.√32 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.8
  18. 18.Best estimate of 600 ÷ 26? (a) 20 (b) 2000 (c) 200
  19. 19.Best estimate of 3193 ÷ 73? (a) 4600 (b) 46 (c) 460
  20. 20.√20 to 1 decimal place? (a) 4.3 (b) 4.4 (c) 4.6 (d) 4.5
  21. 21.Best estimate of 1451 ÷ 26? (a) 4800 (b) 48 (c) 480
  22. 22.Best estimate of 2284 ÷ 52? (a) 460 (b) 4600 (c) 46
  23. 23.Best estimate of 5665 ÷ 86? (a) 6300 (b) 63 (c) 630
  24. 24.Best estimate of 2409 ÷ 33? (a) 80 (b) 800 (c) 8000
  25. 25.Best estimate of 1803 ÷ 46? (a) 360 (b) 3600 (c) 36
  26. 26.Best estimate of 2765 ÷ 39? (a) 6900 (b) 690 (c) 69
  27. 27.Best estimate of 3438 ÷ 41? (a) 8600 (b) 860 (c) 86
  28. 28.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  29. 29.√40 to 1 decimal place? (a) 6.4 (b) 6.6 (c) 6.3 (d) 6.5
  30. 30.√21 to 1 decimal place? (a) 4.3 (b) 4.6 (c) 4.4 (d) 4.5
  31. 31.Best estimate of 6187 ÷ 67? (a) 88 (b) 8800 (c) 880
  32. 32.√79 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.9 (d) 9.1
  33. 33.Best estimate of 5274 ÷ 56? (a) 8800 (b) 88 (c) 880
  34. 34.Best estimate of 2521 ÷ 33? (a) 8400 (b) 84 (c) 840
  35. 35.√62 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.0 (d) 8.1
  36. 36.Best estimate of 4774 ÷ 61? (a) 800 (b) 8000 (c) 80
  37. 37.Best estimate of 3613 ÷ 79? (a) 45 (b) 4500 (c) 450
  38. 38.Best estimate of 863 ÷ 27? (a) 290 (b) 2900 (c) 29
  39. 39.√85 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.4 (d) 9.3
  40. 40.Best estimate of 3545 ÷ 62? (a) 59 (b) 590 (c) 5900

Answer key

  1. 45
  2. 55
  3. 7.9
  4. 100
  5. 16
  6. 59
  7. 9.3
  8. 14
  9. 55
  10. 6.5
  11. 5.2
  12. 33
  13. 5.3
  14. 74
  15. 19
  16. 5.8
  17. 5.7
  18. 20
  19. 46
  20. 4.5
  21. 48
  22. 46
  23. 63
  24. 80
  25. 36
  26. 69
  27. 86
  28. 7.6
  29. 6.3
  30. 4.6
  31. 88
  32. 8.9
  33. 88
  34. 84
  35. 7.9
  36. 80
  37. 45
  38. 29
  39. 9.2
  40. 59

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