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Estimating Square Roots and Division Worksheet

Mental maths lesson 27: Estimate divisions and square roots · Set 769 · 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.√47 to 1 decimal place? (a) 6.6 (b) 6.8 (c) 6.7 (d) 6.9
  2. 2.Best estimate of 2995 ÷ 67? (a) 430 (b) 4300 (c) 43
  3. 3.√76 to 1 decimal place? (a) 8.8 (b) 8.6 (c) 8.5 (d) 8.7
  4. 4.Best estimate of 1746 ÷ 82? (a) 2200 (b) 22 (c) 220
  5. 5.Best estimate of 2077 ÷ 24? (a) 1040 (b) 10400 (c) 104
  6. 6.√98 to 1 decimal place? (a) 10.1 (b) 9.9 (c) 10.0 (d) 10.2
  7. 7.√66 to 1 decimal place? (a) 7.9 (b) 8.0 (c) 8.1 (d) 7.8
  8. 8.√34 to 1 decimal place? (a) 6.1 (b) 5.9 (c) 5.8 (d) 6.0
  9. 9.Best estimate of 3789 ÷ 62? (a) 6300 (b) 630 (c) 63
  10. 10.Best estimate of 3812 ÷ 79? (a) 4800 (b) 480 (c) 48
  11. 11.Best estimate of 4808 ÷ 59? (a) 800 (b) 80 (c) 8000
  12. 12.Best estimate of 3247 ÷ 42? (a) 81 (b) 810 (c) 8100
  13. 13.Best estimate of 1934 ÷ 22? (a) 97 (b) 970 (c) 9700
  14. 14.Best estimate of 7937 ÷ 84? (a) 99 (b) 9900 (c) 990
  15. 15.√65 to 1 decimal place? (a) 8.1 (b) 8.0 (c) 8.3 (d) 8.2
  16. 16.Best estimate of 4773 ÷ 63? (a) 80 (b) 8000 (c) 800
  17. 17.Best estimate of 1511 ÷ 24? (a) 760 (b) 76 (c) 7600
  18. 18.Best estimate of 970 ÷ 28? (a) 32 (b) 3200 (c) 320
  19. 19.√23 to 1 decimal place? (a) 4.9 (b) 4.7 (c) 4.6 (d) 4.8
  20. 20.Best estimate of 2231 ÷ 41? (a) 56 (b) 5600 (c) 560
  21. 21.√26 to 1 decimal place? (a) 5.1 (b) 5.0 (c) 5.2 (d) 4.9
  22. 22.Best estimate of 3888 ÷ 86? (a) 43 (b) 4300 (c) 430
  23. 23.Best estimate of 1563 ÷ 37? (a) 3900 (b) 390 (c) 39
  24. 24.Best estimate of 745 ÷ 44? (a) 19 (b) 190 (c) 1900
  25. 25.√51 to 1 decimal place? (a) 7.3 (b) 7.1 (c) 7.2 (d) 7.0
  26. 26.√28 to 1 decimal place? (a) 5.2 (b) 5.0 (c) 5.3 (d) 5.1
  27. 27.Best estimate of 1770 ÷ 32? (a) 59 (b) 590 (c) 5900
  28. 28.Best estimate of 2313 ÷ 34? (a) 77 (b) 770 (c) 7700
  29. 29.Best estimate of 3932 ÷ 42? (a) 980 (b) 9800 (c) 98
  30. 30.Best estimate of 1054 ÷ 49? (a) 2100 (b) 21 (c) 210
  31. 31.Best estimate of 1407 ÷ 63? (a) 23 (b) 2300 (c) 230
  32. 32.Best estimate of 2218 ÷ 67? (a) 32 (b) 3200 (c) 320
  33. 33.Best estimate of 4439 ÷ 72? (a) 6300 (b) 63 (c) 630
  34. 34.√90 to 1 decimal place? (a) 9.6 (b) 9.3 (c) 9.5 (d) 9.4
  35. 35.√27 to 1 decimal place? (a) 5.4 (b) 5.2 (c) 5.3 (d) 5.5
  36. 36.Best estimate of 1553 ÷ 23? (a) 78 (b) 7800 (c) 780
  37. 37.Best estimate of 1947 ÷ 31? (a) 650 (b) 6500 (c) 65
  38. 38.√71 to 1 decimal place? (a) 8.6 (b) 8.5 (c) 8.7 (d) 8.4
  39. 39.Best estimate of 433 ÷ 26? (a) 1400 (b) 140 (c) 14
  40. 40.√75 to 1 decimal place? (a) 8.8 (b) 8.7 (c) 9.0 (d) 8.9

Answer key

  1. 6.9
  2. 43
  3. 8.7
  4. 22
  5. 104
  6. 9.9
  7. 8.1
  8. 5.8
  9. 63
  10. 48
  11. 80
  12. 81
  13. 97
  14. 99
  15. 8.1
  16. 80
  17. 76
  18. 32
  19. 4.8
  20. 56
  21. 5.1
  22. 43
  23. 39
  24. 19
  25. 7.1
  26. 5.3
  27. 59
  28. 77
  29. 98
  30. 21
  31. 23
  32. 32
  33. 63
  34. 9.5
  35. 5.2
  36. 78
  37. 65
  38. 8.4
  39. 14
  40. 8.7

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