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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 536 · 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 1955 ÷ 21? (a) 98 (b) 980 (c) 9800
  2. 2.Best estimate of 1632 ÷ 21? (a) 820 (b) 8200 (c) 82
  3. 3.√61 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  4. 4.Best estimate of 943 ÷ 58? (a) 1600 (b) 160 (c) 16
  5. 5.√74 to 1 decimal place? (a) 8.7 (b) 8.6 (c) 8.9 (d) 8.8
  6. 6.Best estimate of 1481 ÷ 21? (a) 7400 (b) 74 (c) 740
  7. 7.Best estimate of 880 ÷ 58? (a) 15 (b) 1500 (c) 150
  8. 8.√92 to 1 decimal place? (a) 9.8 (b) 9.6 (c) 9.9 (d) 9.7
  9. 9.Best estimate of 449 ÷ 21? (a) 22 (b) 2200 (c) 220
  10. 10.Best estimate of 1921 ÷ 34? (a) 6400 (b) 64 (c) 640
  11. 11.√43 to 1 decimal place? (a) 6.6 (b) 6.3 (c) 6.4 (d) 6.5
  12. 12.Best estimate of 1220 ÷ 34? (a) 410 (b) 4100 (c) 41
  13. 13.√42 to 1 decimal place? (a) 6.8 (b) 6.6 (c) 6.5 (d) 6.7
  14. 14.√58 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.4
  15. 15.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 8.8 (d) 8.9
  16. 16.Best estimate of 1329 ÷ 33? (a) 44 (b) 440 (c) 4400
  17. 17.Best estimate of 384 ÷ 26? (a) 130 (b) 13 (c) 1300
  18. 18.Best estimate of 949 ÷ 32? (a) 320 (b) 32 (c) 3200
  19. 19.√80 to 1 decimal place? (a) 8.8 (b) 9.1 (c) 8.9 (d) 9.0
  20. 20.Best estimate of 5883 ÷ 76? (a) 74 (b) 7400 (c) 740
  21. 21.√98 to 1 decimal place? (a) 9.8 (b) 9.7 (c) 9.9 (d) 9.6
  22. 22.√22 to 1 decimal place? (a) 4.6 (b) 4.9 (c) 4.8 (d) 4.7
  23. 23.Best estimate of 4451 ÷ 56? (a) 74 (b) 740 (c) 7400
  24. 24.Best estimate of 4149 ÷ 87? (a) 46 (b) 460 (c) 4600
  25. 25.√79 to 1 decimal place? (a) 8.8 (b) 9.1 (c) 8.9 (d) 9.0
  26. 26.Best estimate of 1442 ÷ 27? (a) 4800 (b) 48 (c) 480
  27. 27.√88 to 1 decimal place? (a) 9.5 (b) 9.4 (c) 9.2 (d) 9.3
  28. 28.Best estimate of 1727 ÷ 43? (a) 4300 (b) 43 (c) 430
  29. 29.√96 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.6 (d) 9.8
  30. 30.√66 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.3 (d) 8.2
  31. 31.Best estimate of 823 ÷ 64? (a) 14 (b) 140 (c) 1400
  32. 32.Best estimate of 2281 ÷ 46? (a) 460 (b) 4600 (c) 46
  33. 33.Best estimate of 1071 ÷ 52? (a) 21 (b) 2100 (c) 210
  34. 34.Best estimate of 2511 ÷ 32? (a) 8400 (b) 84 (c) 840
  35. 35.Best estimate of 1890 ÷ 47? (a) 3800 (b) 38 (c) 380
  36. 36.Best estimate of 4587 ÷ 53? (a) 92 (b) 920 (c) 9200
  37. 37.√76 to 1 decimal place? (a) 8.6 (b) 8.7 (c) 8.9 (d) 8.8
  38. 38.Best estimate of 7065 ÷ 84? (a) 88 (b) 880 (c) 8800
  39. 39.√72 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.6 (d) 8.8
  40. 40.√40 to 1 decimal place? (a) 6.3 (b) 6.2 (c) 6.0 (d) 6.1

Answer key

  1. 98
  2. 82
  3. 7.8
  4. 16
  5. 8.6
  6. 74
  7. 15
  8. 9.6
  9. 22
  10. 64
  11. 6.6
  12. 41
  13. 6.5
  14. 7.6
  15. 9.1
  16. 44
  17. 13
  18. 32
  19. 8.9
  20. 74
  21. 9.9
  22. 4.7
  23. 74
  24. 46
  25. 8.9
  26. 48
  27. 9.4
  28. 43
  29. 9.8
  30. 8.1
  31. 14
  32. 46
  33. 21
  34. 84
  35. 38
  36. 92
  37. 8.7
  38. 88
  39. 8.5
  40. 6.3

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