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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 146 · 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.√40 to 1 decimal place? (a) 6.6 (b) 6.4 (c) 6.5 (d) 6.3
  2. 2.√24 to 1 decimal place? (a) 5.0 (b) 4.8 (c) 5.1 (d) 4.9
  3. 3.Best estimate of 3052 ÷ 46? (a) 6100 (b) 610 (c) 61
  4. 4.√94 to 1 decimal place? (a) 9.7 (b) 9.9 (c) 9.6 (d) 9.8
  5. 5.Best estimate of 1356 ÷ 42? (a) 3400 (b) 34 (c) 340
  6. 6.√58 to 1 decimal place? (a) 7.7 (b) 7.6 (c) 7.8 (d) 7.5
  7. 7.Best estimate of 1690 ÷ 52? (a) 34 (b) 340 (c) 3400
  8. 8.Best estimate of 1650 ÷ 36? (a) 410 (b) 4100 (c) 41
  9. 9.Best estimate of 682 ÷ 22? (a) 3400 (b) 34 (c) 340
  10. 10.√34 to 1 decimal place? (a) 6.0 (b) 6.1 (c) 5.8 (d) 5.9
  11. 11.Best estimate of 2816 ÷ 31? (a) 9400 (b) 94 (c) 940
  12. 12.Best estimate of 1562 ÷ 32? (a) 5200 (b) 520 (c) 52
  13. 13.√87 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  14. 14.√69 to 1 decimal place? (a) 8.1 (b) 8.2 (c) 8.3 (d) 8.4
  15. 15.Best estimate of 458 ÷ 23? (a) 230 (b) 2300 (c) 23
  16. 16.Best estimate of 743 ÷ 52? (a) 15 (b) 1500 (c) 150
  17. 17.Best estimate of 1885 ÷ 34? (a) 630 (b) 63 (c) 6300
  18. 18.√82 to 1 decimal place? (a) 9.2 (b) 9.1 (c) 9.0 (d) 9.3
  19. 19.Best estimate of 1423 ÷ 39? (a) 36 (b) 360 (c) 3600
  20. 20.√92 to 1 decimal place? (a) 9.4 (b) 9.5 (c) 9.3 (d) 9.6
  21. 21.Best estimate of 1636 ÷ 26? (a) 550 (b) 55 (c) 5500
  22. 22.Best estimate of 6580 ÷ 87? (a) 730 (b) 73 (c) 7300
  23. 23.√62 to 1 decimal place? (a) 8.0 (b) 7.8 (c) 7.9 (d) 8.1
  24. 24.Best estimate of 2000 ÷ 46? (a) 400 (b) 4000 (c) 40
  25. 25.√79 to 1 decimal place? (a) 9.0 (b) 9.2 (c) 8.9 (d) 9.1
  26. 26.Best estimate of 4104 ÷ 69? (a) 590 (b) 5900 (c) 59
  27. 27.√50 to 1 decimal place? (a) 7.4 (b) 7.1 (c) 7.2 (d) 7.3
  28. 28.Best estimate of 1978 ÷ 52? (a) 400 (b) 4000 (c) 40
  29. 29.Best estimate of 4308 ÷ 63? (a) 720 (b) 72 (c) 7200
  30. 30.Best estimate of 1763 ÷ 21? (a) 8800 (b) 88 (c) 880
  31. 31.√84 to 1 decimal place? (a) 9.1 (b) 9.3 (c) 9.4 (d) 9.2
  32. 32.√71 to 1 decimal place? (a) 8.5 (b) 8.2 (c) 8.3 (d) 8.4
  33. 33.Best estimate of 1094 ÷ 37? (a) 2700 (b) 270 (c) 27
  34. 34.√20 to 1 decimal place? (a) 4.7 (b) 4.6 (c) 4.8 (d) 4.5
  35. 35.Best estimate of 5558 ÷ 61? (a) 93 (b) 930 (c) 9300
  36. 36.√29 to 1 decimal place? (a) 5.5 (b) 5.6 (c) 5.4 (d) 5.7
  37. 37.√96 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.7 (d) 9.6
  38. 38.√41 to 1 decimal place? (a) 6.6 (b) 6.7 (c) 6.4 (d) 6.5
  39. 39.Best estimate of 6030 ÷ 66? (a) 86 (b) 8600 (c) 860
  40. 40.√42 to 1 decimal place? (a) 6.4 (b) 6.3 (c) 6.5 (d) 6.6

Answer key

  1. 6.3
  2. 4.9
  3. 61
  4. 9.7
  5. 34
  6. 7.6
  7. 34
  8. 41
  9. 34
  10. 5.8
  11. 94
  12. 52
  13. 9.3
  14. 8.3
  15. 23
  16. 15
  17. 63
  18. 9.1
  19. 36
  20. 9.6
  21. 55
  22. 73
  23. 7.9
  24. 40
  25. 8.9
  26. 59
  27. 7.1
  28. 40
  29. 72
  30. 88
  31. 9.2
  32. 8.4
  33. 27
  34. 4.5
  35. 93
  36. 5.4
  37. 9.8
  38. 6.4
  39. 86
  40. 6.5

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