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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 923 · 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.√83 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.3 (d) 9.2
  2. 2.√51 to 1 decimal place? (a) 7.3 (b) 7.0 (c) 7.1 (d) 7.2
  3. 3.Best estimate of 1048 ÷ 21? (a) 52 (b) 520 (c) 5200
  4. 4.Best estimate of 2346 ÷ 58? (a) 390 (b) 39 (c) 3900
  5. 5.Best estimate of 2015 ÷ 42? (a) 5000 (b) 500 (c) 50
  6. 6.√90 to 1 decimal place? (a) 9.3 (b) 9.5 (c) 9.4 (d) 9.2
  7. 7.√69 to 1 decimal place? (a) 8.1 (b) 8.3 (c) 8.2 (d) 8.4
  8. 8.Best estimate of 2194 ÷ 36? (a) 550 (b) 55 (c) 5500
  9. 9.Best estimate of 1436 ÷ 27? (a) 48 (b) 480 (c) 4800
  10. 10.Best estimate of 851 ÷ 33? (a) 280 (b) 28 (c) 2800
  11. 11.Best estimate of 1604 ÷ 47? (a) 32 (b) 3200 (c) 320
  12. 12.√47 to 1 decimal place? (a) 6.9 (b) 7.0 (c) 6.8 (d) 7.1
  13. 13.Best estimate of 935 ÷ 32? (a) 310 (b) 3100 (c) 31
  14. 14.√75 to 1 decimal place? (a) 8.5 (b) 8.8 (c) 8.7 (d) 8.6
  15. 15.√58 to 1 decimal place? (a) 7.6 (b) 7.3 (c) 7.5 (d) 7.4
  16. 16.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.1 (d) 6.2
  17. 17.Best estimate of 5366 ÷ 78? (a) 6700 (b) 670 (c) 67
  18. 18.Best estimate of 1019 ÷ 27? (a) 340 (b) 34 (c) 3400
  19. 19.Best estimate of 8485 ÷ 89? (a) 940 (b) 94 (c) 9400
  20. 20.√66 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.0 (d) 8.3
  21. 21.√53 to 1 decimal place? (a) 7.2 (b) 7.3 (c) 7.0 (d) 7.1
  22. 22.Best estimate of 890 ÷ 31? (a) 30 (b) 300 (c) 3000
  23. 23.Best estimate of 5499 ÷ 84? (a) 6900 (b) 690 (c) 69
  24. 24.Best estimate of 904 ÷ 26? (a) 30 (b) 3000 (c) 300
  25. 25.Best estimate of 2867 ÷ 44? (a) 72 (b) 720 (c) 7200
  26. 26.Best estimate of 1368 ÷ 31? (a) 460 (b) 46 (c) 4600
  27. 27.Best estimate of 1549 ÷ 46? (a) 310 (b) 3100 (c) 31
  28. 28.Best estimate of 1898 ÷ 59? (a) 32 (b) 320 (c) 3200
  29. 29.Best estimate of 2510 ÷ 61? (a) 420 (b) 4200 (c) 42
  30. 30.Best estimate of 935 ÷ 72? (a) 1300 (b) 130 (c) 13
  31. 31.Best estimate of 2132 ÷ 34? (a) 7100 (b) 710 (c) 71
  32. 32.Best estimate of 4003 ÷ 52? (a) 80 (b) 8000 (c) 800
  33. 33.Best estimate of 1627 ÷ 26? (a) 540 (b) 54 (c) 5400
  34. 34.Best estimate of 425 ÷ 21? (a) 21 (b) 210 (c) 2100
  35. 35.√78 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.8 (d) 8.6
  36. 36.Best estimate of 8136 ÷ 88? (a) 900 (b) 90 (c) 9000
  37. 37.Best estimate of 837 ÷ 39? (a) 210 (b) 21 (c) 2100
  38. 38.√44 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.7
  39. 39.Best estimate of 1932 ÷ 89? (a) 21 (b) 2100 (c) 210
  40. 40.Best estimate of 3348 ÷ 44? (a) 8400 (b) 84 (c) 840

Answer key

  1. 9.1
  2. 7.1
  3. 52
  4. 39
  5. 50
  6. 9.5
  7. 8.3
  8. 55
  9. 48
  10. 28
  11. 32
  12. 6.9
  13. 31
  14. 8.7
  15. 7.6
  16. 6.2
  17. 67
  18. 34
  19. 94
  20. 8.1
  21. 7.3
  22. 30
  23. 69
  24. 30
  25. 72
  26. 46
  27. 31
  28. 32
  29. 42
  30. 13
  31. 71
  32. 80
  33. 54
  34. 21
  35. 8.8
  36. 90
  37. 21
  38. 6.6
  39. 21
  40. 84

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