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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 831 · 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. 1.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  2. 2.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  3. 3.Leapfrog list (each number is the sum of the two before it): 4, 2, 6, 8, 14, 22, 36, 58, 94, 152. What is 11 × the 7th number?
  4. 4.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?
  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.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. 7.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  8. 8.2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 =
  9. 9.A leapfrog list starts 9, 6 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 6, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.A leapfrog list starts 6, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  13. 13.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  14. 14.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?
  15. 15.8 + 1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 =
  16. 16.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?
  17. 17.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?
  18. 18.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  19. 19.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?
  20. 20.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  21. 21.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?
  22. 22.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?
  23. 23.8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 + 474 =
  24. 24.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?
  25. 25.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  26. 26.Leapfrog list (each number is the sum of the two before it): 1, 7, 8, 15, 23, 38, 61, 99, 160, 259. What is 11 × the 7th number?
  27. 27.Leapfrog list (each number is the sum of the two before it): 8, 1, 9, 10, 19, 29, 48, 77, 125, 202. What is 11 × the 7th number?
  28. 28.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?
  29. 29.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?
  30. 30.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  31. 31.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?
  32. 32.A leapfrog list starts 8, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  34. 34.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  35. 35.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  36. 36.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?
  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 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  39. 39.8 + 5 + 13 + 18 + 31 + 49 + 80 + 129 + 209 + 338 =
  40. 40.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?

Answer key

  1. 847
  2. 946
  3. 396
  4. 869
  5. 1144
  6. 583
  7. 1056
  8. 550
  9. 1023
  10. 858
  11. 946
  12. 814
  13. 1144
  14. 891
  15. 528
  16. 1287
  17. 319
  18. 583
  19. 759
  20. 517
  21. 946
  22. 1199
  23. 1232
  24. 374
  25. 396
  26. 671
  27. 528
  28. 1122
  29. 506
  30. 198
  31. 418
  32. 1144
  33. 1023
  34. 451
  35. 759
  36. 594
  37. 143
  38. 902
  39. 880
  40. 451

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