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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 170 · 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): 8, 3, 11, 14, 25, 39, 64, 103, 167, 270. What is 11 × the 7th number?
  2. 2.A leapfrog list starts 2, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  3. 3.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  4. 4.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?
  5. 5.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  6. 6.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?
  7. 7.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  8. 8.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  9. 9.A leapfrog list starts 1, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  10. 10.Leapfrog list (each number is the sum of the two before it): 5, 5, 10, 15, 25, 40, 65, 105, 170, 275. What is 11 × the 7th number?
  11. 11.Leapfrog list (each number is the sum of the two before it): 7, 1, 8, 9, 17, 26, 43, 69, 112, 181. What is 11 × the 7th number?
  12. 12.Leapfrog list (each number is the sum of the two before it): 1, 8, 9, 17, 26, 43, 69, 112, 181, 293. What is 11 × the 7th number?
  13. 13.3 + 1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 =
  14. 14.1 + 1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 =
  15. 15.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  16. 16.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?
  17. 17.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  18. 18.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  19. 19.Leapfrog list (each number is the sum of the two before it): 6, 1, 7, 8, 15, 23, 38, 61, 99, 160. What is 11 × the 7th number?
  20. 20.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?
  21. 21.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  22. 22.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  23. 23.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?
  24. 24.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  25. 25.A leapfrog list starts 6, 5 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): 1, 4, 5, 9, 14, 23, 37, 60, 97, 157. What is 11 × the 7th number?
  27. 27.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  28. 28.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?
  29. 29.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?
  30. 30.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?
  31. 31.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?
  32. 32.1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 + 191 =
  33. 33.A leapfrog list starts 1, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  34. 34.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?
  35. 35.Leapfrog list (each number is the sum of the two before it): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  36. 36.Leapfrog list (each number is the sum of the two before it): 1, 5, 6, 11, 17, 28, 45, 73, 118, 191. What is 11 × the 7th number?
  37. 37.A leapfrog list starts 1, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.A leapfrog list starts 9, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  40. 40.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =

Answer key

  1. 704
  2. 902
  3. 946
  4. 561
  5. 429
  6. 583
  7. 847
  8. 550
  9. 143
  10. 715
  11. 473
  12. 759
  13. 253
  14. 143
  15. 561
  16. 583
  17. 693
  18. 1144
  19. 418
  20. 451
  21. 594
  22. 231
  23. 429
  24. 1199
  25. 770
  26. 407
  27. 517
  28. 374
  29. 308
  30. 319
  31. 825
  32. 495
  33. 231
  34. 1287
  35. 968
  36. 495
  37. 847
  38. 671
  39. 792
  40. 451

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