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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 472 · 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 4125 ÷ 46? (a) 8300 (b) 830 (c) 83
  2. 2.Best estimate of 1715 ÷ 22? (a) 8600 (b) 86 (c) 860
  3. 3.Best estimate of 2700 ÷ 72? (a) 3900 (b) 390 (c) 39
  4. 4.√88 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  5. 5.√28 to 1 decimal place? (a) 5.5 (b) 5.2 (c) 5.3 (d) 5.4
  6. 6.Best estimate of 2216 ÷ 56? (a) 3700 (b) 370 (c) 37
  7. 7.Best estimate of 4686 ÷ 51? (a) 940 (b) 9400 (c) 94
  8. 8.Best estimate of 1048 ÷ 51? (a) 210 (b) 2100 (c) 21
  9. 9.Best estimate of 3255 ÷ 36? (a) 810 (b) 81 (c) 8100
  10. 10.Best estimate of 2685 ÷ 87? (a) 300 (b) 30 (c) 3000
  11. 11.Best estimate of 801 ÷ 36? (a) 20 (b) 2000 (c) 200
  12. 12.Best estimate of 3492 ÷ 53? (a) 700 (b) 70 (c) 7000
  13. 13.Best estimate of 342 ÷ 24? (a) 1700 (b) 17 (c) 170
  14. 14.Best estimate of 4051 ÷ 43? (a) 1010 (b) 101 (c) 10100
  15. 15.√58 to 1 decimal place? (a) 7.4 (b) 7.6 (c) 7.7 (d) 7.5
  16. 16.√85 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.5 (d) 9.3
  17. 17.Best estimate of 2832 ÷ 41? (a) 7100 (b) 710 (c) 71
  18. 18.√77 to 1 decimal place? (a) 9.1 (b) 8.9 (c) 8.8 (d) 9.0
  19. 19.Best estimate of 4317 ÷ 49? (a) 86 (b) 860 (c) 8600
  20. 20.Best estimate of 793 ÷ 23? (a) 40 (b) 4000 (c) 400
  21. 21.√61 to 1 decimal place? (a) 7.9 (b) 7.8 (c) 8.0 (d) 8.1
  22. 22.√40 to 1 decimal place? (a) 6.1 (b) 6.2 (c) 6.4 (d) 6.3
  23. 23.Best estimate of 633 ÷ 22? (a) 32 (b) 320 (c) 3200
  24. 24.Best estimate of 3953 ÷ 73? (a) 56 (b) 560 (c) 5600
  25. 25.√51 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.4 (d) 7.1
  26. 26.Best estimate of 5336 ÷ 68? (a) 7600 (b) 760 (c) 76
  27. 27.Best estimate of 896 ÷ 26? (a) 300 (b) 3000 (c) 30
  28. 28.Best estimate of 1940 ÷ 67? (a) 28 (b) 280 (c) 2800
  29. 29.√55 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  30. 30.√26 to 1 decimal place? (a) 4.9 (b) 5.1 (c) 4.8 (d) 5.0
  31. 31.Best estimate of 1142 ÷ 69? (a) 160 (b) 16 (c) 1600
  32. 32.√84 to 1 decimal place? (a) 9.4 (b) 9.3 (c) 9.1 (d) 9.2
  33. 33.Best estimate of 6312 ÷ 68? (a) 90 (b) 9000 (c) 900
  34. 34.√66 to 1 decimal place? (a) 8.3 (b) 8.1 (c) 8.2 (d) 8.4
  35. 35.Best estimate of 6104 ÷ 83? (a) 760 (b) 76 (c) 7600
  36. 36.Best estimate of 6321 ÷ 67? (a) 90 (b) 9000 (c) 900
  37. 37.Best estimate of 6050 ÷ 73? (a) 860 (b) 8600 (c) 86
  38. 38.√75 to 1 decimal place? (a) 8.5 (b) 8.7 (c) 8.8 (d) 8.6
  39. 39.Best estimate of 1408 ÷ 56? (a) 230 (b) 23 (c) 2300
  40. 40.Best estimate of 3128 ÷ 58? (a) 5200 (b) 520 (c) 52

Answer key

  1. 83
  2. 86
  3. 39
  4. 9.4
  5. 5.3
  6. 37
  7. 94
  8. 21
  9. 81
  10. 30
  11. 20
  12. 70
  13. 17
  14. 101
  15. 7.6
  16. 9.2
  17. 71
  18. 8.8
  19. 86
  20. 40
  21. 7.8
  22. 6.3
  23. 32
  24. 56
  25. 7.1
  26. 76
  27. 30
  28. 28
  29. 7.4
  30. 5.1
  31. 16
  32. 9.2
  33. 90
  34. 8.1
  35. 76
  36. 90
  37. 86
  38. 8.7
  39. 23
  40. 52

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