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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 82 · 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.√55 to 1 decimal place? (a) 7.7 (b) 7.4 (c) 7.6 (d) 7.5
  2. 2.√59 to 1 decimal place? (a) 7.5 (b) 7.6 (c) 7.7 (d) 7.4
  3. 3.Best estimate of 2702 ÷ 47? (a) 540 (b) 5400 (c) 54
  4. 4.Best estimate of 6194 ÷ 89? (a) 6900 (b) 690 (c) 69
  5. 5.Best estimate of 1506 ÷ 27? (a) 50 (b) 500 (c) 5000
  6. 6.Best estimate of 846 ÷ 34? (a) 28 (b) 280 (c) 2800
  7. 7.√74 to 1 decimal place? (a) 8.6 (b) 8.8 (c) 8.9 (d) 8.7
  8. 8.Best estimate of 2997 ÷ 33? (a) 10000 (b) 1000 (c) 100
  9. 9.√34 to 1 decimal place? (a) 5.6 (b) 5.7 (c) 5.5 (d) 5.8
  10. 10.√80 to 1 decimal place? (a) 9.0 (b) 8.7 (c) 8.8 (d) 8.9
  11. 11.Best estimate of 1381 ÷ 64? (a) 23 (b) 2300 (c) 230
  12. 12.√94 to 1 decimal place? (a) 9.5 (b) 9.8 (c) 9.6 (d) 9.7
  13. 13.√82 to 1 decimal place? (a) 9.1 (b) 9.2 (c) 9.3 (d) 9.0
  14. 14.Best estimate of 993 ÷ 36? (a) 2500 (b) 250 (c) 25
  15. 15.Best estimate of 1431 ÷ 51? (a) 2900 (b) 290 (c) 29
  16. 16.Best estimate of 4060 ÷ 81? (a) 51 (b) 510 (c) 5100
  17. 17.√40 to 1 decimal place? (a) 6.2 (b) 6.5 (c) 6.3 (d) 6.4
  18. 18.Best estimate of 1498 ÷ 21? (a) 7500 (b) 75 (c) 750
  19. 19.Best estimate of 1463 ÷ 61? (a) 240 (b) 2400 (c) 24
  20. 20.Best estimate of 2159 ÷ 47? (a) 430 (b) 4300 (c) 43
  21. 21.√92 to 1 decimal place? (a) 9.9 (b) 9.8 (c) 9.6 (d) 9.7
  22. 22.Best estimate of 3919 ÷ 68? (a) 56 (b) 560 (c) 5600
  23. 23.Best estimate of 656 ÷ 38? (a) 16 (b) 160 (c) 1600
  24. 24.Best estimate of 1178 ÷ 37? (a) 290 (b) 29 (c) 2900
  25. 25.Best estimate of 1591 ÷ 26? (a) 530 (b) 5300 (c) 53
  26. 26.Best estimate of 2695 ÷ 81? (a) 340 (b) 34 (c) 3400
  27. 27.√21 to 1 decimal place? (a) 4.5 (b) 4.3 (c) 4.6 (d) 4.4
  28. 28.√37 to 1 decimal place? (a) 5.9 (b) 6.0 (c) 6.1 (d) 6.2
  29. 29.√43 to 1 decimal place? (a) 6.7 (b) 6.6 (c) 6.5 (d) 6.8
  30. 30.√89 to 1 decimal place? (a) 9.4 (b) 9.2 (c) 9.5 (d) 9.3
  31. 31.Best estimate of 695 ÷ 43? (a) 170 (b) 1700 (c) 17
  32. 32.Best estimate of 2342 ÷ 38? (a) 590 (b) 5900 (c) 59
  33. 33.√65 to 1 decimal place? (a) 8.2 (b) 8.3 (c) 8.1 (d) 8.0
  34. 34.Best estimate of 3846 ÷ 67? (a) 550 (b) 55 (c) 5500
  35. 35.Best estimate of 1228 ÷ 42? (a) 310 (b) 31 (c) 3100
  36. 36.Best estimate of 4394 ÷ 62? (a) 730 (b) 7300 (c) 73
  37. 37.√28 to 1 decimal place? (a) 5.3 (b) 5.1 (c) 5.2 (d) 5.0
  38. 38.Best estimate of 3864 ÷ 66? (a) 550 (b) 5500 (c) 55
  39. 39.Best estimate of 1717 ÷ 33? (a) 570 (b) 5700 (c) 57
  40. 40.Best estimate of 2235 ÷ 68? (a) 3200 (b) 32 (c) 320

Answer key

  1. 7.4
  2. 7.7
  3. 54
  4. 69
  5. 50
  6. 28
  7. 8.6
  8. 100
  9. 5.8
  10. 8.9
  11. 23
  12. 9.7
  13. 9.1
  14. 25
  15. 29
  16. 51
  17. 6.3
  18. 75
  19. 24
  20. 43
  21. 9.6
  22. 56
  23. 16
  24. 29
  25. 53
  26. 34
  27. 4.6
  28. 6.1
  29. 6.6
  30. 9.4
  31. 17
  32. 59
  33. 8.1
  34. 55
  35. 31
  36. 73
  37. 5.3
  38. 55
  39. 57
  40. 32

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