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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 887 · 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 3385 ÷ 49? (a) 6800 (b) 68 (c) 680
  2. 2.√69 to 1 decimal place? (a) 8.5 (b) 8.3 (c) 8.6 (d) 8.4
  3. 3.Best estimate of 1029 ÷ 39? (a) 260 (b) 26 (c) 2600
  4. 4.Best estimate of 3630 ÷ 69? (a) 5200 (b) 52 (c) 520
  5. 5.√65 to 1 decimal place? (a) 8.0 (b) 8.1 (c) 8.2 (d) 7.9
  6. 6.√26 to 1 decimal place? (a) 5.0 (b) 5.2 (c) 5.3 (d) 5.1
  7. 7.Best estimate of 2113 ÷ 86? (a) 2300 (b) 230 (c) 23
  8. 8.Best estimate of 953 ÷ 33? (a) 3200 (b) 32 (c) 320
  9. 9.Best estimate of 2419 ÷ 56? (a) 400 (b) 40 (c) 4000
  10. 10.Best estimate of 1107 ÷ 26? (a) 370 (b) 37 (c) 3700
  11. 11.Best estimate of 985 ÷ 62? (a) 1600 (b) 160 (c) 16
  12. 12.Best estimate of 5287 ÷ 62? (a) 880 (b) 88 (c) 8800
  13. 13.√87 to 1 decimal place? (a) 9.1 (b) 9.4 (c) 9.2 (d) 9.3
  14. 14.Best estimate of 5411 ÷ 58? (a) 900 (b) 90 (c) 9000
  15. 15.√80 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.9 (d) 8.7
  16. 16.Best estimate of 4102 ÷ 78? (a) 510 (b) 51 (c) 5100
  17. 17.Best estimate of 1233 ÷ 49? (a) 25 (b) 250 (c) 2500
  18. 18.√82 to 1 decimal place? (a) 9.1 (b) 9.0 (c) 9.2 (d) 8.9
  19. 19.Best estimate of 2100 ÷ 28? (a) 7000 (b) 70 (c) 700
  20. 20.Best estimate of 2269 ÷ 79? (a) 2800 (b) 28 (c) 280
  21. 21.Best estimate of 2429 ÷ 54? (a) 490 (b) 4900 (c) 49
  22. 22.Best estimate of 5141 ÷ 84? (a) 6400 (b) 640 (c) 64
  23. 23.√30 to 1 decimal place? (a) 5.5 (b) 5.8 (c) 5.7 (d) 5.6
  24. 24.Best estimate of 1934 ÷ 36? (a) 48 (b) 480 (c) 4800
  25. 25.√24 to 1 decimal place? (a) 4.8 (b) 4.9 (c) 5.0 (d) 4.7
  26. 26.Best estimate of 1829 ÷ 26? (a) 61 (b) 610 (c) 6100
  27. 27.Best estimate of 514 ÷ 37? (a) 1300 (b) 130 (c) 13
  28. 28.√79 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 8.7 (d) 8.9
  29. 29.Best estimate of 1138 ÷ 42? (a) 2800 (b) 280 (c) 28
  30. 30.Best estimate of 2723 ÷ 31? (a) 91 (b) 910 (c) 9100
  31. 31.√52 to 1 decimal place? (a) 7.4 (b) 7.1 (c) 7.3 (d) 7.2
  32. 32.√48 to 1 decimal place? (a) 7.2 (b) 7.0 (c) 7.1 (d) 6.9
  33. 33.√38 to 1 decimal place? (a) 6.3 (b) 6.4 (c) 6.2 (d) 6.1
  34. 34.√94 to 1 decimal place? (a) 9.5 (b) 9.7 (c) 9.6 (d) 9.8
  35. 35.Best estimate of 3612 ÷ 72? (a) 520 (b) 52 (c) 5200
  36. 36.√55 to 1 decimal place? (a) 7.3 (b) 7.2 (c) 7.4 (d) 7.1
  37. 37.√42 to 1 decimal place? (a) 6.2 (b) 6.3 (c) 6.5 (d) 6.4
  38. 38.√40 to 1 decimal place? (a) 6.2 (b) 6.5 (c) 6.4 (d) 6.3
  39. 39.Best estimate of 2021 ÷ 64? (a) 3400 (b) 340 (c) 34
  40. 40.√78 to 1 decimal place? (a) 8.8 (b) 9.0 (c) 9.1 (d) 8.9

Answer key

  1. 68
  2. 8.3
  3. 26
  4. 52
  5. 8.1
  6. 5.1
  7. 23
  8. 32
  9. 40
  10. 37
  11. 16
  12. 88
  13. 9.3
  14. 90
  15. 8.9
  16. 51
  17. 25
  18. 9.1
  19. 70
  20. 28
  21. 49
  22. 64
  23. 5.5
  24. 48
  25. 4.9
  26. 61
  27. 13
  28. 8.9
  29. 28
  30. 91
  31. 7.2
  32. 6.9
  33. 6.2
  34. 9.7
  35. 52
  36. 7.4
  37. 6.5
  38. 6.3
  39. 34
  40. 8.8

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