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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 700 · 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. 1.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  2. 2.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?
  3. 3.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?
  4. 4.5 + 4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 =
  5. 5.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  6. 6.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  7. 7.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  8. 8.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  9. 9.5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 + 377 =
  10. 10.6 + 5 + 11 + 16 + 27 + 43 + 70 + 113 + 183 + 296 =
  11. 11.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.A leapfrog list starts 1, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.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?
  14. 14.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  15. 15.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?
  16. 16.A leapfrog list starts 4, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  17. 17.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  18. 18.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?
  19. 19.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  20. 20.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  21. 21.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?
  22. 22.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?
  23. 23.A leapfrog list starts 5, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.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?
  25. 25.A leapfrog list starts 3, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  27. 27.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  28. 28.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  29. 29.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?
  30. 30.1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 =
  31. 31.A leapfrog list starts 9, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  32. 32.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  33. 33.7 + 3 + 10 + 13 + 23 + 36 + 59 + 95 + 154 + 249 =
  34. 34.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?
  35. 35.A leapfrog list starts 2, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.A leapfrog list starts 2, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  38. 38.A leapfrog list starts 7, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.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?
  40. 40.Leapfrog list (each number is the sum of the two before it): 6, 7, 13, 20, 33, 53, 86, 139, 225, 364. What is 11 × the 7th number?

Answer key

  1. 374
  2. 462
  3. 671
  4. 627
  5. 583
  6. 891
  7. 1034
  8. 495
  9. 979
  10. 770
  11. 616
  12. 319
  13. 451
  14. 1199
  15. 473
  16. 1012
  17. 231
  18. 506
  19. 550
  20. 858
  21. 1199
  22. 814
  23. 451
  24. 825
  25. 869
  26. 660
  27. 1232
  28. 407
  29. 429
  30. 319
  31. 583
  32. 286
  33. 649
  34. 638
  35. 550
  36. 286
  37. 539
  38. 737
  39. 374
  40. 946

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