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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 353 · 40 questions
TalentJR

The trick (Seventh times eleven): A leapfrog list: start with two numbers, then each number is the sum of the two before it, up to 10 numbers. Find the 7th number. Multiply it by 11 (the number with a 0 on the end, plus the number): that is the total of all 10.

NameDateTime takenScore ___ / 40
  1. 1.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  2. 2.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  3. 3.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  4. 4.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 5, 8, 13, 21, 34, 55, 89, 144, 233, 377. What is 11 × the 7th number?
  6. 6.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  7. 7.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  8. 8.Leapfrog list (each number is the sum of the two before it): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  9. 9.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  10. 10.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  11. 11.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  12. 12.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  13. 13.A leapfrog list starts 8, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.Leapfrog list (each number is the sum of the two before it): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  15. 15.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  16. 16.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  18. 18.A leapfrog list starts 6, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  19. 19.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  20. 20.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  21. 21.Leapfrog list (each number is the sum of the two before it): 1, 6, 7, 13, 20, 33, 53, 86, 139, 225. What is 11 × the 7th number?
  22. 22.Leapfrog list (each number is the sum of the two before it): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  23. 23.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  25. 25.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 9, 1, 10, 11, 21, 32, 53, 85, 138, 223. What is 11 × the 7th number?
  27. 27.A leapfrog list starts 2, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  29. 29.Leapfrog list (each number is the sum of the two before it): 6, 8, 14, 22, 36, 58, 94, 152, 246, 398. What is 11 × the 7th number?
  30. 30.A leapfrog list starts 9, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  31. 31.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  32. 32.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  33. 33.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  34. 34.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  35. 35.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  36. 36.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  38. 38.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  39. 39.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =

Answer key

  1. 308
  2. 671
  3. 286
  4. 396
  5. 979
  6. 759
  7. 528
  8. 704
  9. 418
  10. 495
  11. 484
  12. 1089
  13. 528
  14. 605
  15. 1199
  16. 1034
  17. 869
  18. 1034
  19. 1001
  20. 935
  21. 583
  22. 561
  23. 891
  24. 726
  25. 880
  26. 583
  27. 374
  28. 517
  29. 1034
  30. 1199
  31. 539
  32. 473
  33. 1111
  34. 374
  35. 737
  36. 308
  37. 759
  38. 550
  39. 407
  40. 935

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