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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 815 · 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. 1.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  2. 2.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  3. 3.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  4. 4.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  5. 5.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  6. 6.A leapfrog list starts 5, 8 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): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  8. 8.Leapfrog list (each number is the sum of the two before it): 5, 7, 12, 19, 31, 50, 81, 131, 212, 343. What is 11 × the 7th number?
  9. 9.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?
  10. 10.A leapfrog list starts 9, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  12. 12.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  13. 13.A leapfrog list starts 6, 6 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): 7, 2, 9, 11, 20, 31, 51, 82, 133, 215. What is 11 × the 7th number?
  15. 15.A leapfrog list starts 6, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.Leapfrog list (each number is the sum of the two before it): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  17. 17.A leapfrog list starts 8, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.Leapfrog list (each number is the sum of the two before it): 1, 9, 10, 19, 29, 48, 77, 125, 202, 327. What is 11 × the 7th number?
  19. 19.5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 + 309 =
  20. 20.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  21. 21.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?
  22. 22.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  23. 23.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?
  24. 24.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  25. 25.A leapfrog list starts 1, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  27. 27.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?
  28. 28.Leapfrog list (each number is the sum of the two before it): 4, 3, 7, 10, 17, 27, 44, 71, 115, 186. What is 11 × the 7th number?
  29. 29.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  30. 30.Leapfrog list (each number is the sum of the two before it): 7, 5, 12, 17, 29, 46, 75, 121, 196, 317. What is 11 × the 7th number?
  31. 31.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  32. 32.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  33. 33.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  34. 34.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  35. 35.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  36. 36.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?
  37. 37.A leapfrog list starts 5, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  39. 39.5 + 5 + 10 + 15 + 25 + 40 + 65 + 105 + 170 + 275 =
  40. 40.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =

Answer key

  1. 759
  2. 1177
  3. 1023
  4. 671
  5. 1144
  6. 979
  7. 693
  8. 891
  9. 1089
  10. 1287
  11. 583
  12. 1232
  13. 858
  14. 561
  15. 1122
  16. 231
  17. 1232
  18. 847
  19. 803
  20. 561
  21. 143
  22. 550
  23. 319
  24. 946
  25. 583
  26. 880
  27. 506
  28. 484
  29. 814
  30. 825
  31. 539
  32. 418
  33. 341
  34. 924
  35. 891
  36. 550
  37. 539
  38. 374
  39. 715
  40. 1034

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