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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 28 · 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.A leapfrog list starts 2, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  2. 2.Leapfrog list (each number is the sum of the two before it): 2, 5, 7, 12, 19, 31, 50, 81, 131, 212. What is 11 × the 7th number?
  3. 3.6 + 6 + 12 + 18 + 30 + 48 + 78 + 126 + 204 + 330 =
  4. 4.1 + 2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 =
  5. 5.9 + 3 + 12 + 15 + 27 + 42 + 69 + 111 + 180 + 291 =
  6. 6.A leapfrog list starts 7, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  7. 7.4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 + 254 =
  8. 8.A leapfrog list starts 3, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  9. 9.5 + 1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 =
  10. 10.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?
  11. 11.A leapfrog list starts 8, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  12. 12.A leapfrog list starts 6, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.4 + 2 + 6 + 8 + 14 + 22 + 36 + 58 + 94 + 152 =
  14. 14.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?
  15. 15.Leapfrog list (each number is the sum of the two before it): 6, 6, 12, 18, 30, 48, 78, 126, 204, 330. What is 11 × the 7th number?
  16. 16.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?
  17. 17.3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 + 301 =
  18. 18.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?
  19. 19.Leapfrog list (each number is the sum of the two before it): 9, 7, 16, 23, 39, 62, 101, 163, 264, 427. What is 11 × the 7th number?
  20. 20.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  21. 21.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?
  22. 22.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?
  23. 23.9 + 2 + 11 + 13 + 24 + 37 + 61 + 98 + 159 + 257 =
  24. 24.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?
  25. 25.6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 + 364 =
  26. 26.A leapfrog list starts 8, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  27. 27.A leapfrog list starts 5, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  28. 28.4 + 4 + 8 + 12 + 20 + 32 + 52 + 84 + 136 + 220 =
  29. 29.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  30. 30.4 + 9 + 13 + 22 + 35 + 57 + 92 + 149 + 241 + 390 =
  31. 31.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  32. 32.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?
  33. 33.Leapfrog list (each number is the sum of the two before it): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  34. 34.Leapfrog list (each number is the sum of the two before it): 6, 5, 11, 16, 27, 43, 70, 113, 183, 296. What is 11 × the 7th number?
  35. 35.2 + 3 + 5 + 8 + 13 + 21 + 34 + 55 + 89 + 144 =
  36. 36.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?
  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. 38.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  39. 39.A leapfrog list starts 7, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  40. 40.8 + 3 + 11 + 14 + 25 + 39 + 64 + 103 + 167 + 270 =

Answer key

  1. 638
  2. 550
  3. 858
  4. 231
  5. 759
  6. 561
  7. 660
  8. 517
  9. 363
  10. 462
  11. 616
  12. 594
  13. 396
  14. 968
  15. 858
  16. 858
  17. 781
  18. 946
  19. 1111
  20. 1056
  21. 374
  22. 495
  23. 671
  24. 451
  25. 946
  26. 704
  27. 363
  28. 572
  29. 1177
  30. 1012
  31. 539
  32. 231
  33. 539
  34. 770
  35. 374
  36. 341
  37. 759
  38. 1122
  39. 473
  40. 704

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