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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 266 · 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. 1.6 + 1 + 7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 =
  2. 2.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?
  3. 3.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  4. 4.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?
  5. 5.8 + 4 + 12 + 16 + 28 + 44 + 72 + 116 + 188 + 304 =
  6. 6.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?
  7. 7.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  8. 8.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?
  9. 9.A leapfrog list starts 8, 5 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): 8, 6, 14, 20, 34, 54, 88, 142, 230, 372. What is 11 × the 7th number?
  11. 11.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?
  12. 12.Leapfrog list (each number is the sum of the two before it): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  13. 13.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  14. 14.A leapfrog list starts 4, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.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?
  16. 16.Leapfrog list (each number is the sum of the two before it): 9, 3, 12, 15, 27, 42, 69, 111, 180, 291. What is 11 × the 7th number?
  17. 17.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?
  18. 18.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  19. 19.A leapfrog list starts 5, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.A leapfrog list starts 8, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  21. 21.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?
  22. 22.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  23. 23.A leapfrog list starts 2, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  24. 24.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  25. 25.Leapfrog list (each number is the sum of the two before it): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  26. 26.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =
  27. 27.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?
  28. 28.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  29. 29.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?
  30. 30.Leapfrog list (each number is the sum of the two before it): 3, 7, 10, 17, 27, 44, 71, 115, 186, 301. What is 11 × the 7th number?
  31. 31.7 + 1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 =
  32. 32.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  33. 33.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?
  34. 34.Leapfrog list (each number is the sum of the two before it): 9, 6, 15, 21, 36, 57, 93, 150, 243, 393. What is 11 × the 7th number?
  35. 35.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?
  36. 36.A leapfrog list starts 4, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  37. 37.A leapfrog list starts 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  38. 38.7 + 8 + 15 + 23 + 38 + 61 + 99 + 160 + 259 + 419 =
  39. 39.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?
  40. 40.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?

Answer key

  1. 418
  2. 517
  3. 506
  4. 737
  5. 792
  6. 825
  7. 363
  8. 1012
  9. 880
  10. 968
  11. 451
  12. 1001
  13. 1144
  14. 396
  15. 1144
  16. 759
  17. 528
  18. 572
  19. 891
  20. 968
  21. 671
  22. 1067
  23. 814
  24. 759
  25. 605
  26. 704
  27. 583
  28. 341
  29. 583
  30. 781
  31. 473
  32. 781
  33. 770
  34. 1023
  35. 462
  36. 484
  37. 759
  38. 1089
  39. 869
  40. 143

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