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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 626 · 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 1721 ÷ 21? (a) 8600 (b) 860 (c) 86
  2. 2.Best estimate of 1085 ÷ 23? (a) 540 (b) 5400 (c) 54
  3. 3.Best estimate of 1715 ÷ 54? (a) 3400 (b) 340 (c) 34
  4. 4.√74 to 1 decimal place? (a) 8.7 (b) 8.8 (c) 8.6 (d) 8.5
  5. 5.√82 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.1 (d) 9.2
  6. 6.Best estimate of 2824 ÷ 34? (a) 940 (b) 9400 (c) 94
  7. 7.√96 to 1 decimal place? (a) 10.0 (b) 9.9 (c) 9.8 (d) 10.1
  8. 8.Best estimate of 3376 ÷ 52? (a) 680 (b) 68 (c) 6800
  9. 9.√85 to 1 decimal place? (a) 9.0 (b) 9.3 (c) 9.1 (d) 9.2
  10. 10.√58 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.7 (d) 7.6
  11. 11.Best estimate of 912 ÷ 62? (a) 15 (b) 150 (c) 1500
  12. 12.Best estimate of 3350 ÷ 72? (a) 480 (b) 48 (c) 4800
  13. 13.Best estimate of 5731 ÷ 76? (a) 720 (b) 7200 (c) 72
  14. 14.Best estimate of 453 ÷ 36? (a) 1100 (b) 110 (c) 11
  15. 15.Best estimate of 1313 ÷ 32? (a) 440 (b) 4400 (c) 44
  16. 16.Best estimate of 2571 ÷ 38? (a) 64 (b) 6400 (c) 640
  17. 17.√55 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.4 (d) 7.3
  18. 18.Best estimate of 3449 ÷ 43? (a) 8600 (b) 86 (c) 860
  19. 19.Best estimate of 1917 ÷ 26? (a) 640 (b) 6400 (c) 64
  20. 20.Best estimate of 464 ÷ 32? (a) 1500 (b) 150 (c) 15
  21. 21.√92 to 1 decimal place? (a) 9.7 (b) 9.8 (c) 9.5 (d) 9.6
  22. 22.√77 to 1 decimal place? (a) 9.0 (b) 8.8 (c) 8.7 (d) 8.9
  23. 23.√89 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.4
  24. 24.√80 to 1 decimal place? (a) 8.8 (b) 8.9 (c) 9.1 (d) 9.0
  25. 25.√65 to 1 decimal place? (a) 8.3 (b) 8.2 (c) 8.1 (d) 8.4
  26. 26.Best estimate of 1541 ÷ 39? (a) 3900 (b) 39 (c) 390
  27. 27.Best estimate of 2947 ÷ 78? (a) 3700 (b) 370 (c) 37
  28. 28.√98 to 1 decimal place? (a) 9.7 (b) 9.6 (c) 9.8 (d) 9.9
  29. 29.Best estimate of 2421 ÷ 33? (a) 8100 (b) 81 (c) 810
  30. 30.√62 to 1 decimal place? (a) 7.8 (b) 7.7 (c) 7.9 (d) 8.0
  31. 31.√26 to 1 decimal place? (a) 5.1 (b) 5.2 (c) 5.0 (d) 5.3
  32. 32.Best estimate of 1415 ÷ 42? (a) 35 (b) 3500 (c) 350
  33. 33.Best estimate of 2533 ÷ 42? (a) 6300 (b) 63 (c) 630
  34. 34.Best estimate of 1087 ÷ 53? (a) 2200 (b) 220 (c) 22
  35. 35.Best estimate of 2383 ÷ 62? (a) 40 (b) 400 (c) 4000
  36. 36.Best estimate of 548 ÷ 31? (a) 180 (b) 1800 (c) 18
  37. 37.Best estimate of 2038 ÷ 73? (a) 2900 (b) 29 (c) 290
  38. 38.Best estimate of 2774 ÷ 66? (a) 4000 (b) 40 (c) 400
  39. 39.Best estimate of 3738 ÷ 46? (a) 7500 (b) 750 (c) 75
  40. 40.√44 to 1 decimal place? (a) 6.5 (b) 6.7 (c) 6.6 (d) 6.8

Answer key

  1. 86
  2. 54
  3. 34
  4. 8.6
  5. 9.1
  6. 94
  7. 9.8
  8. 68
  9. 9.2
  10. 7.6
  11. 15
  12. 48
  13. 72
  14. 11
  15. 44
  16. 64
  17. 7.4
  18. 86
  19. 64
  20. 15
  21. 9.6
  22. 8.8
  23. 9.4
  24. 8.9
  25. 8.1
  26. 39
  27. 37
  28. 9.9
  29. 81
  30. 7.9
  31. 5.1
  32. 35
  33. 63
  34. 22
  35. 40
  36. 18
  37. 29
  38. 40
  39. 75
  40. 6.6

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