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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 924 · 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): 3, 8, 11, 19, 30, 49, 79, 128, 207, 335. What is 11 × the 7th number?
  2. 2.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  3. 3.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  4. 4.3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 + 233 =
  5. 5.A leapfrog list starts 5, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  6. 6.A leapfrog list starts 3, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.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?
  8. 8.4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 + 356 =
  9. 9.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?
  10. 10.A leapfrog list starts 4, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  11. 11.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  12. 12.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?
  13. 13.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?
  14. 14.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  15. 15.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  16. 16.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  17. 17.Leapfrog list (each number is the sum of the two before it): 9, 5, 14, 19, 33, 52, 85, 137, 222, 359. What is 11 × the 7th number?
  18. 18.1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 =
  19. 19.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  20. 20.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?
  21. 21.Leapfrog list (each number is the sum of the two before it): 2, 1, 3, 4, 7, 11, 18, 29, 47, 76. What is 11 × the 7th number?
  22. 22.A leapfrog list starts 6, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  23. 23.Leapfrog list (each number is the sum of the two before it): 7, 3, 10, 13, 23, 36, 59, 95, 154, 249. What is 11 × the 7th number?
  24. 24.A leapfrog list starts 3, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.A leapfrog list starts 1, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  26. 26.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 7, 4, 11, 15, 26, 41, 67, 108, 175, 283. What is 11 × the 7th number?
  28. 28.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?
  29. 29.9 + 4 + 13 + 17 + 30 + 47 + 77 + 124 + 201 + 325 =
  30. 30.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?
  31. 31.Leapfrog list (each number is the sum of the two before it): 3, 4, 7, 11, 18, 29, 47, 76, 123, 199. What is 11 × the 7th number?
  32. 32.Leapfrog list (each number is the sum of the two before it): 2, 3, 5, 8, 13, 21, 34, 55, 89, 144. What is 11 × the 7th number?
  33. 33.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  34. 34.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  35. 35.6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 + 398 =
  36. 36.7 + 2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 =
  37. 37.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  38. 38.A leapfrog list starts 4, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  39. 39.Leapfrog list (each number is the sum of the two before it): 2, 9, 11, 20, 31, 51, 82, 133, 215, 348. What is 11 × the 7th number?
  40. 40.7 + 7 + 14 + 21 + 35 + 56 + 91 + 147 + 238 + 385 =

Answer key

  1. 869
  2. 1111
  3. 1199
  4. 605
  5. 803
  6. 605
  7. 231
  8. 924
  9. 484
  10. 748
  11. 704
  12. 891
  13. 495
  14. 231
  15. 759
  16. 308
  17. 935
  18. 671
  19. 418
  20. 572
  21. 198
  22. 418
  23. 649
  24. 253
  25. 759
  26. 946
  27. 737
  28. 594
  29. 847
  30. 671
  31. 517
  32. 374
  33. 968
  34. 407
  35. 1034
  36. 561
  37. 484
  38. 572
  39. 902
  40. 1001

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