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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 520 · 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. 1.8 + 6 + 14 + 20 + 34 + 54 + 88 + 142 + 230 + 372 =
  2. 2.5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 + 212 + 343 =
  3. 3.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?
  4. 4.2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 + 246 =
  5. 5.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?
  6. 6.4 + 1 + 5 + 6 + 11 + 17 + 28 + 45 + 73 + 118 =
  7. 7.4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 + 322 =
  8. 8.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?
  9. 9.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  10. 10.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  11. 11.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  12. 12.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?
  13. 13.Leapfrog list (each number is the sum of the two before it): 8, 7, 15, 22, 37, 59, 96, 155, 251, 406. What is 11 × the 7th number?
  14. 14.A leapfrog list starts 7, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  15. 15.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  16. 16.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?
  17. 17.8 + 2 + 10 + 12 + 22 + 34 + 56 + 90 + 146 + 236 =
  18. 18.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?
  19. 19.Leapfrog list (each number is the sum of the two before it): 8, 5, 13, 18, 31, 49, 80, 129, 209, 338. What is 11 × the 7th number?
  20. 20.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  21. 21.5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 + 411 =
  22. 22.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  23. 23.5 + 2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 =
  24. 24.A leapfrog list starts 4, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.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?
  26. 26.3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 =
  27. 27.Leapfrog list (each number is the sum of the two before it): 2, 2, 4, 6, 10, 16, 26, 42, 68, 110. What is 11 × the 7th number?
  28. 28.A leapfrog list starts 7, 8 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): 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. What is 11 × the 7th number?
  30. 30.A leapfrog list starts 8, 1 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): 3, 5, 8, 13, 21, 34, 55, 89, 144, 233. What is 11 × the 7th number?
  32. 32.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?
  33. 33.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?
  34. 34.Leapfrog list (each number is the sum of the two before it): 4, 8, 12, 20, 32, 52, 84, 136, 220, 356. What is 11 × the 7th number?
  35. 35.A leapfrog list starts 2, 7 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  36. 36.2 + 2 + 4 + 6 + 10 + 16 + 26 + 42 + 68 + 110 =
  37. 37.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?
  38. 38.1 + 9 + 10 + 19 + 29 + 48 + 77 + 125 + 202 + 327 =
  39. 39.A leapfrog list starts 3, 2 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): 9, 9, 18, 27, 45, 72, 117, 189, 306, 495. What is 11 × the 7th number?

Answer key

  1. 968
  2. 891
  3. 781
  4. 638
  5. 891
  6. 308
  7. 836
  8. 583
  9. 737
  10. 374
  11. 429
  12. 671
  13. 1056
  14. 649
  15. 671
  16. 561
  17. 616
  18. 198
  19. 880
  20. 583
  21. 1067
  22. 1012
  23. 451
  24. 924
  25. 517
  26. 693
  27. 286
  28. 1089
  29. 231
  30. 528
  31. 605
  32. 759
  33. 473
  34. 924
  35. 726
  36. 286
  37. 759
  38. 847
  39. 341
  40. 1287

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