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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 21 · 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 1470 ÷ 51? (a) 29 (b) 2900 (c) 290
  2. 2.√20 to 1 decimal place? (a) 4.5 (b) 4.4 (c) 4.6 (d) 4.7
  3. 3.√51 to 1 decimal place? (a) 7.0 (b) 7.1 (c) 6.9 (d) 6.8
  4. 4.√41 to 1 decimal place? (a) 6.5 (b) 6.4 (c) 6.6 (d) 6.7
  5. 5.Best estimate of 1661 ÷ 82? (a) 2100 (b) 210 (c) 21
  6. 6.Best estimate of 1959 ÷ 34? (a) 65 (b) 650 (c) 6500
  7. 7.√28 to 1 decimal place? (a) 5.0 (b) 5.1 (c) 5.3 (d) 5.2
  8. 8.Best estimate of 797 ÷ 22? (a) 400 (b) 4000 (c) 40
  9. 9.Best estimate of 4967 ÷ 59? (a) 8300 (b) 830 (c) 83
  10. 10.√66 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  11. 11.Best estimate of 1847 ÷ 48? (a) 37 (b) 370 (c) 3700
  12. 12.√69 to 1 decimal place? (a) 8.3 (b) 8.4 (c) 8.2 (d) 8.5
  13. 13.√55 to 1 decimal place? (a) 7.6 (b) 7.4 (c) 7.5 (d) 7.7
  14. 14.Best estimate of 2641 ÷ 71? (a) 38 (b) 380 (c) 3800
  15. 15.Best estimate of 6924 ÷ 82? (a) 8700 (b) 87 (c) 870
  16. 16.Best estimate of 2003 ÷ 82? (a) 2500 (b) 25 (c) 250
  17. 17.Best estimate of 342 ÷ 24? (a) 170 (b) 17 (c) 1700
  18. 18.√47 to 1 decimal place? (a) 6.7 (b) 6.9 (c) 6.8 (d) 6.6
  19. 19.Best estimate of 862 ÷ 26? (a) 2900 (b) 29 (c) 290
  20. 20.Best estimate of 480 ÷ 31? (a) 1600 (b) 16 (c) 160
  21. 21.Best estimate of 1685 ÷ 66? (a) 2400 (b) 240 (c) 24
  22. 22.Best estimate of 3876 ÷ 79? (a) 480 (b) 4800 (c) 48
  23. 23.Best estimate of 1683 ÷ 52? (a) 34 (b) 3400 (c) 340
  24. 24.√23 to 1 decimal place? (a) 4.6 (b) 4.7 (c) 4.8 (d) 4.5
  25. 25.Best estimate of 3599 ÷ 73? (a) 510 (b) 51 (c) 5100
  26. 26.Best estimate of 3005 ÷ 56? (a) 500 (b) 50 (c) 5000
  27. 27.Best estimate of 1485 ÷ 72? (a) 210 (b) 2100 (c) 21
  28. 28.√48 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.9 (d) 6.7
  29. 29.√65 to 1 decimal place? (a) 8.2 (b) 7.9 (c) 8.1 (d) 8.0
  30. 30.√88 to 1 decimal place? (a) 9.7 (b) 9.5 (c) 9.4 (d) 9.6
  31. 31.Best estimate of 3292 ÷ 46? (a) 66 (b) 660 (c) 6600
  32. 32.√96 to 1 decimal place? (a) 10.0 (b) 9.8 (c) 9.9 (d) 9.7
  33. 33.Best estimate of 1684 ÷ 39? (a) 42 (b) 420 (c) 4200
  34. 34.Best estimate of 7271 ÷ 83? (a) 91 (b) 910 (c) 9100
  35. 35.Best estimate of 2492 ÷ 52? (a) 5000 (b) 50 (c) 500
  36. 36.Best estimate of 3220 ÷ 72? (a) 46 (b) 460 (c) 4600
  37. 37.√45 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.7 (d) 6.8
  38. 38.Best estimate of 1987 ÷ 26? (a) 66 (b) 660 (c) 6600
  39. 39.Best estimate of 1810 ÷ 56? (a) 3000 (b) 30 (c) 300
  40. 40.Best estimate of 1184 ÷ 21? (a) 59 (b) 590 (c) 5900

Answer key

  1. 29
  2. 4.5
  3. 7.1
  4. 6.4
  5. 21
  6. 65
  7. 5.3
  8. 40
  9. 83
  10. 8.1
  11. 37
  12. 8.3
  13. 7.4
  14. 38
  15. 87
  16. 25
  17. 17
  18. 6.9
  19. 29
  20. 16
  21. 24
  22. 48
  23. 34
  24. 4.8
  25. 51
  26. 50
  27. 21
  28. 6.9
  29. 8.1
  30. 9.4
  31. 66
  32. 9.8
  33. 42
  34. 91
  35. 50
  36. 46
  37. 6.7
  38. 66
  39. 30
  40. 59

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