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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 264 · 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.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 1, 3, 4, 7, 11, 18, 29, 47, 76, 123. What is 11 × the 7th number?
  3. 3.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  4. 4.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  5. 5.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  6. 6.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  8. 8.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  9. 9.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  11. 11.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  12. 12.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?
  13. 13.A leapfrog list starts 4, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  14. 14.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  15. 15.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  16. 16.A leapfrog list starts 5, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  18. 18.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  20. 20.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  21. 21.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  22. 22.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  23. 23.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  24. 24.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 9, 8, 17, 25, 42, 67, 109, 176, 285, 461. What is 11 × the 7th number?
  26. 26.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?
  27. 27.Leapfrog list (each number is the sum of the two before it): 5, 6, 11, 17, 28, 45, 73, 118, 191, 309. What is 11 × the 7th number?
  28. 28.Leapfrog list (each number is the sum of the two before it): 8, 2, 10, 12, 22, 34, 56, 90, 146, 236. What is 11 × the 7th number?
  29. 29.Leapfrog list (each number is the sum of the two before it): 4, 7, 11, 18, 29, 47, 76, 123, 199, 322. What is 11 × the 7th number?
  30. 30.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  31. 31.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.A leapfrog list starts 5, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  34. 34.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  35. 35.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  36. 36.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  37. 37.Leapfrog list (each number is the sum of the two before it): 3, 3, 6, 9, 15, 24, 39, 63, 102, 165. What is 11 × the 7th number?
  38. 38.A leapfrog list starts 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  40. 40.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =

Answer key

  1. 286
  2. 319
  3. 231
  4. 286
  5. 880
  6. 638
  7. 363
  8. 550
  9. 506
  10. 638
  11. 429
  12. 605
  13. 660
  14. 506
  15. 1111
  16. 1067
  17. 1232
  18. 1199
  19. 451
  20. 143
  21. 363
  22. 748
  23. 594
  24. 814
  25. 1199
  26. 374
  27. 803
  28. 616
  29. 836
  30. 935
  31. 517
  32. 627
  33. 847
  34. 407
  35. 660
  36. 1177
  37. 429
  38. 473
  39. 1034
  40. 770

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