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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 444 · 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): 5, 2, 7, 9, 16, 25, 41, 66, 107, 173. What is 11 × the 7th number?
  2. 2.Leapfrog list (each number is the sum of the two before it): 3, 9, 12, 21, 33, 54, 87, 141, 228, 369. What is 11 × the 7th number?
  3. 3.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  4. 4.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  5. 5.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?
  6. 6.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  7. 7.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  8. 8.A leapfrog list starts 7, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  10. 10.A leapfrog list starts 3, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  12. 12.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  13. 13.Leapfrog list (each number is the sum of the two before it): 6, 3, 9, 12, 21, 33, 54, 87, 141, 228. What is 11 × the 7th number?
  14. 14.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  15. 15.Leapfrog list (each number is the sum of the two before it): 2, 8, 10, 18, 28, 46, 74, 120, 194, 314. What is 11 × the 7th number?
  16. 16.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?
  17. 17.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  18. 18.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  19. 19.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  20. 20.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?
  21. 21.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  22. 22.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  23. 23.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  24. 24.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?
  25. 25.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 2, 4, 6, 10, 16, 26, 42, 68, 110, 178. What is 11 × the 7th number?
  27. 27.Leapfrog list (each number is the sum of the two before it): 4, 5, 9, 14, 23, 37, 60, 97, 157, 254. What is 11 × the 7th number?
  28. 28.Leapfrog list (each number is the sum of the two before it): 6, 4, 10, 14, 24, 38, 62, 100, 162, 262. What is 11 × the 7th number?
  29. 29.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 4, 4, 8, 12, 20, 32, 52, 84, 136, 220. What is 11 × the 7th number?
  31. 31.4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 + 178 + 288 =
  32. 32.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  33. 33.Leapfrog list (each number is the sum of the two before it): 9, 2, 11, 13, 24, 37, 61, 98, 159, 257. What is 11 × the 7th number?
  34. 34.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  35. 35.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  36. 36.A leapfrog list starts 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.Leapfrog list (each number is the sum of the two before it): 1, 1, 2, 3, 5, 8, 13, 21, 34, 55. What is 11 × the 7th number?
  38. 38.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  39. 39.Leapfrog list (each number is the sum of the two before it): 8, 9, 17, 26, 43, 69, 112, 181, 293, 474. What is 11 × the 7th number?
  40. 40.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =

Answer key

  1. 451
  2. 957
  3. 825
  4. 319
  5. 429
  6. 539
  7. 517
  8. 1089
  9. 649
  10. 341
  11. 693
  12. 308
  13. 594
  14. 671
  15. 814
  16. 1199
  17. 1122
  18. 891
  19. 594
  20. 374
  21. 418
  22. 1089
  23. 506
  24. 550
  25. 1199
  26. 462
  27. 660
  28. 682
  29. 528
  30. 572
  31. 748
  32. 583
  33. 671
  34. 737
  35. 253
  36. 495
  37. 143
  38. 814
  39. 1232
  40. 198

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