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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 809 · 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 3279 ÷ 62? (a) 5500 (b) 550 (c) 55
  2. 2.√79 to 1 decimal place? (a) 9.1 (b) 8.8 (c) 8.9 (d) 9.0
  3. 3.√76 to 1 decimal place? (a) 8.6 (b) 8.4 (c) 8.5 (d) 8.7
  4. 4.Best estimate of 6247 ÷ 74? (a) 890 (b) 89 (c) 8900
  5. 5.√92 to 1 decimal place? (a) 9.6 (b) 9.7 (c) 9.8 (d) 9.5
  6. 6.Best estimate of 2652 ÷ 37? (a) 6600 (b) 66 (c) 660
  7. 7.√24 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 4.7 (d) 4.6
  8. 8.Best estimate of 3245 ÷ 36? (a) 8100 (b) 81 (c) 810
  9. 9.√34 to 1 decimal place? (a) 5.7 (b) 5.6 (c) 5.8 (d) 5.5
  10. 10.√72 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.5 (d) 8.7
  11. 11.√56 to 1 decimal place? (a) 7.5 (b) 7.4 (c) 7.6 (d) 7.7
  12. 12.√88 to 1 decimal place? (a) 9.3 (b) 9.4 (c) 9.5 (d) 9.6
  13. 13.Best estimate of 432 ÷ 21? (a) 22 (b) 220 (c) 2200
  14. 14.Best estimate of 3334 ÷ 62? (a) 5600 (b) 56 (c) 560
  15. 15.Best estimate of 542 ÷ 27? (a) 1800 (b) 18 (c) 180
  16. 16.Best estimate of 529 ÷ 44? (a) 130 (b) 13 (c) 1300
  17. 17.Best estimate of 832 ÷ 56? (a) 1400 (b) 14 (c) 140
  18. 18.Best estimate of 5426 ÷ 76? (a) 6800 (b) 680 (c) 68
  19. 19.√47 to 1 decimal place? (a) 7.1 (b) 7.0 (c) 7.2 (d) 6.9
  20. 20.√46 to 1 decimal place? (a) 6.8 (b) 7.0 (c) 6.9 (d) 7.1
  21. 21.Best estimate of 3064 ÷ 64? (a) 51 (b) 5100 (c) 510
  22. 22.√37 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 6.0 (d) 6.2
  23. 23.Best estimate of 1324 ÷ 83? (a) 17 (b) 170 (c) 1700
  24. 24.Best estimate of 918 ÷ 38? (a) 2300 (b) 23 (c) 230
  25. 25.√21 to 1 decimal place? (a) 4.6 (b) 4.5 (c) 4.7 (d) 4.4
  26. 26.Best estimate of 1658 ÷ 21? (a) 83 (b) 8300 (c) 830
  27. 27.Best estimate of 685 ÷ 44? (a) 1700 (b) 17 (c) 170
  28. 28.√75 to 1 decimal place? (a) 8.7 (b) 8.9 (c) 8.6 (d) 8.8
  29. 29.Best estimate of 4397 ÷ 76? (a) 55 (b) 5500 (c) 550
  30. 30.Best estimate of 7946 ÷ 86? (a) 8800 (b) 88 (c) 880
  31. 31.Best estimate of 3544 ÷ 56? (a) 59 (b) 590 (c) 5900
  32. 32.√26 to 1 decimal place? (a) 5.2 (b) 5.4 (c) 5.1 (d) 5.3
  33. 33.√84 to 1 decimal place? (a) 9.3 (b) 9.2 (c) 9.4 (d) 9.1
  34. 34.√78 to 1 decimal place? (a) 8.9 (b) 8.8 (c) 9.0 (d) 8.7
  35. 35.Best estimate of 1294 ÷ 56? (a) 22 (b) 2200 (c) 220
  36. 36.√31 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.9 (d) 5.8
  37. 37.Best estimate of 4126 ÷ 76? (a) 5200 (b) 520 (c) 52
  38. 38.√52 to 1 decimal place? (a) 7.3 (b) 7.4 (c) 7.2 (d) 7.5
  39. 39.Best estimate of 1105 ÷ 52? (a) 220 (b) 22 (c) 2200
  40. 40.√98 to 1 decimal place? (a) 9.9 (b) 10.0 (c) 9.7 (d) 9.8

Answer key

  1. 55
  2. 8.9
  3. 8.7
  4. 89
  5. 9.6
  6. 66
  7. 4.9
  8. 81
  9. 5.8
  10. 8.5
  11. 7.5
  12. 9.4
  13. 22
  14. 56
  15. 18
  16. 13
  17. 14
  18. 68
  19. 6.9
  20. 6.8
  21. 51
  22. 6.1
  23. 17
  24. 23
  25. 4.6
  26. 83
  27. 17
  28. 8.7
  29. 55
  30. 88
  31. 59
  32. 5.1
  33. 9.2
  34. 8.8
  35. 22
  36. 5.6
  37. 52
  38. 7.2
  39. 22
  40. 9.9

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