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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 913 · 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 4208 ÷ 73? (a) 6000 (b) 60 (c) 600
  2. 2.√74 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.4 (d) 8.6
  3. 3.Best estimate of 1123 ÷ 41? (a) 2800 (b) 280 (c) 28
  4. 4.√28 to 1 decimal place? (a) 5.6 (b) 5.5 (c) 5.3 (d) 5.4
  5. 5.Best estimate of 3813 ÷ 84? (a) 480 (b) 4800 (c) 48
  6. 6.Best estimate of 4191 ÷ 69? (a) 6000 (b) 60 (c) 600
  7. 7.Best estimate of 528 ÷ 28? (a) 180 (b) 1800 (c) 18
  8. 8.√94 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.9 (d) 9.6
  9. 9.Best estimate of 1501 ÷ 73? (a) 2100 (b) 21 (c) 210
  10. 10.√80 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 9.0 (d) 8.9
  11. 11.√98 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.7 (d) 9.9
  12. 12.Best estimate of 1153 ÷ 46? (a) 230 (b) 2300 (c) 23
  13. 13.Best estimate of 3990 ÷ 44? (a) 1000 (b) 100 (c) 10000
  14. 14.Best estimate of 827 ÷ 24? (a) 410 (b) 41 (c) 4100
  15. 15.Best estimate of 6900 ÷ 74? (a) 99 (b) 9900 (c) 990
  16. 16.Best estimate of 2808 ÷ 33? (a) 94 (b) 940 (c) 9400
  17. 17.√56 to 1 decimal place? (a) 7.6 (b) 7.5 (c) 7.7 (d) 7.4
  18. 18.Best estimate of 2684 ÷ 84? (a) 3400 (b) 34 (c) 340
  19. 19.√92 to 1 decimal place? (a) 9.4 (b) 9.7 (c) 9.6 (d) 9.5
  20. 20.Best estimate of 722 ÷ 24? (a) 36 (b) 3600 (c) 360
  21. 21.Best estimate of 685 ÷ 44? (a) 1700 (b) 170 (c) 17
  22. 22.√29 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.1
  23. 23.Best estimate of 2097 ÷ 29? (a) 70 (b) 7000 (c) 700
  24. 24.Best estimate of 2054 ÷ 72? (a) 29 (b) 290 (c) 2900
  25. 25.Best estimate of 2580 ÷ 53? (a) 52 (b) 520 (c) 5200
  26. 26.√86 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.2 (d) 9.1
  27. 27.Best estimate of 958 ÷ 31? (a) 32 (b) 3200 (c) 320
  28. 28.√23 to 1 decimal place? (a) 4.5 (b) 4.6 (c) 4.7 (d) 4.8
  29. 29.Best estimate of 819 ÷ 28? (a) 27 (b) 270 (c) 2700
  30. 30.√43 to 1 decimal place? (a) 6.5 (b) 6.8 (c) 6.7 (d) 6.6
  31. 31.Best estimate of 7194 ÷ 82? (a) 9000 (b) 90 (c) 900
  32. 32.Best estimate of 7572 ÷ 82? (a) 950 (b) 95 (c) 9500
  33. 33.Best estimate of 2421 ÷ 44? (a) 61 (b) 6100 (c) 610
  34. 34.√71 to 1 decimal place? (a) 8.4 (b) 8.5 (c) 8.3 (d) 8.6
  35. 35.√46 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  36. 36.Best estimate of 4621 ÷ 67? (a) 660 (b) 6600 (c) 66
  37. 37.Best estimate of 1522 ÷ 42? (a) 38 (b) 380 (c) 3800
  38. 38.Best estimate of 5235 ÷ 62? (a) 87 (b) 870 (c) 8700
  39. 39.Best estimate of 2472 ÷ 27? (a) 8200 (b) 82 (c) 820
  40. 40.√53 to 1 decimal place? (a) 7.3 (b) 7.5 (c) 7.6 (d) 7.4

Answer key

  1. 60
  2. 8.6
  3. 28
  4. 5.3
  5. 48
  6. 60
  7. 18
  8. 9.7
  9. 21
  10. 8.9
  11. 9.9
  12. 23
  13. 100
  14. 41
  15. 99
  16. 94
  17. 7.5
  18. 34
  19. 9.6
  20. 36
  21. 17
  22. 5.4
  23. 70
  24. 29
  25. 52
  26. 9.3
  27. 32
  28. 4.8
  29. 27
  30. 6.6
  31. 90
  32. 95
  33. 61
  34. 8.4
  35. 6.8
  36. 66
  37. 38
  38. 87
  39. 82
  40. 7.3

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