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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 199 · 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 7074 ÷ 77? (a) 880 (b) 88 (c) 8800
  2. 2.Best estimate of 426 ÷ 27? (a) 14 (b) 1400 (c) 140
  3. 3.Best estimate of 1060 ÷ 42? (a) 2700 (b) 27 (c) 270
  4. 4.Best estimate of 1616 ÷ 33? (a) 5400 (b) 54 (c) 540
  5. 5.√52 to 1 decimal place? (a) 6.9 (b) 7.1 (c) 7.0 (d) 7.2
  6. 6.Best estimate of 1086 ÷ 53? (a) 22 (b) 220 (c) 2200
  7. 7.√22 to 1 decimal place? (a) 4.7 (b) 4.9 (c) 4.8 (d) 4.6
  8. 8.Best estimate of 1451 ÷ 51? (a) 290 (b) 29 (c) 2900
  9. 9.Best estimate of 3761 ÷ 87? (a) 420 (b) 4200 (c) 42
  10. 10.√84 to 1 decimal place? (a) 9.2 (b) 9.3 (c) 9.0 (d) 9.1
  11. 11.Best estimate of 3237 ÷ 53? (a) 650 (b) 65 (c) 6500
  12. 12.√61 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.5 (d) 7.8
  13. 13.Best estimate of 1949 ÷ 54? (a) 39 (b) 390 (c) 3900
  14. 14.Best estimate of 7074 ÷ 83? (a) 8800 (b) 88 (c) 880
  15. 15.Best estimate of 909 ÷ 23? (a) 450 (b) 45 (c) 4500
  16. 16.Best estimate of 1192 ÷ 63? (a) 2000 (b) 20 (c) 200
  17. 17.Best estimate of 4009 ÷ 52? (a) 80 (b) 8000 (c) 800
  18. 18.Best estimate of 5081 ÷ 71? (a) 7300 (b) 73 (c) 730
  19. 19.Best estimate of 684 ÷ 22? (a) 34 (b) 3400 (c) 340
  20. 20.√83 to 1 decimal place? (a) 9.2 (b) 9.4 (c) 9.1 (d) 9.3
  21. 21.Best estimate of 2385 ÷ 36? (a) 600 (b) 6000 (c) 60
  22. 22.√72 to 1 decimal place? (a) 8.7 (b) 8.5 (c) 8.8 (d) 8.6
  23. 23.Best estimate of 956 ÷ 31? (a) 32 (b) 320 (c) 3200
  24. 24.Best estimate of 2734 ÷ 29? (a) 9100 (b) 910 (c) 91
  25. 25.Best estimate of 1615 ÷ 21? (a) 81 (b) 810 (c) 8100
  26. 26.Best estimate of 1945 ÷ 77? (a) 24 (b) 2400 (c) 240
  27. 27.Best estimate of 836 ÷ 53? (a) 1700 (b) 17 (c) 170
  28. 28.Best estimate of 1472 ÷ 66? (a) 210 (b) 2100 (c) 21
  29. 29.Best estimate of 4973 ÷ 81? (a) 6200 (b) 620 (c) 62
  30. 30.Best estimate of 4796 ÷ 79? (a) 6000 (b) 600 (c) 60
  31. 31.√47 to 1 decimal place? (a) 6.9 (b) 7.2 (c) 7.1 (d) 7.0
  32. 32.Best estimate of 3788 ÷ 46? (a) 7600 (b) 760 (c) 76
  33. 33.Best estimate of 750 ÷ 34? (a) 25 (b) 2500 (c) 250
  34. 34.Best estimate of 3274 ÷ 73? (a) 47 (b) 4700 (c) 470
  35. 35.Best estimate of 480 ÷ 31? (a) 1600 (b) 160 (c) 16
  36. 36.√79 to 1 decimal place? (a) 8.6 (b) 8.9 (c) 8.8 (d) 8.7
  37. 37.√38 to 1 decimal place? (a) 6.2 (b) 6.1 (c) 6.3 (d) 6.4
  38. 38.Best estimate of 2343 ÷ 27? (a) 78 (b) 780 (c) 7800
  39. 39.Best estimate of 1957 ÷ 39? (a) 490 (b) 49 (c) 4900
  40. 40.√21 to 1 decimal place? (a) 4.5 (b) 4.7 (c) 4.8 (d) 4.6

Answer key

  1. 88
  2. 14
  3. 27
  4. 54
  5. 7.2
  6. 22
  7. 4.7
  8. 29
  9. 42
  10. 9.2
  11. 65
  12. 7.8
  13. 39
  14. 88
  15. 45
  16. 20
  17. 80
  18. 73
  19. 34
  20. 9.1
  21. 60
  22. 8.5
  23. 32
  24. 91
  25. 81
  26. 24
  27. 17
  28. 21
  29. 62
  30. 60
  31. 6.9
  32. 76
  33. 25
  34. 47
  35. 16
  36. 8.9
  37. 6.2
  38. 78
  39. 49
  40. 4.6

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