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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 303 · 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): 5, 3, 8, 11, 19, 30, 49, 79, 128, 207. What is 11 × the 7th number?
  2. 2.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?
  3. 3.7 + 5 + 12 + 17 + 29 + 46 + 75 + 121 + 196 + 317 =
  4. 4.A leapfrog list starts 6, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  5. 5.9 + 5 + 14 + 19 + 33 + 52 + 85 + 137 + 222 + 359 =
  6. 6.Leapfrog list (each number is the sum of the two before it): 3, 2, 5, 7, 12, 19, 31, 50, 81, 131. What is 11 × the 7th number?
  7. 7.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =
  8. 8.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?
  9. 9.2 + 1 + 3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 =
  10. 10.6 + 4 + 10 + 14 + 24 + 38 + 62 + 100 + 162 + 262 =
  11. 11.3 + 4 + 7 + 11 + 18 + 29 + 47 + 76 + 123 + 199 =
  12. 12.A leapfrog list starts 1, 4 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.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?
  14. 14.Leapfrog list (each number is the sum of the two before it): 7, 6, 13, 19, 32, 51, 83, 134, 217, 351. What is 11 × the 7th number?
  15. 15.8 + 7 + 15 + 22 + 37 + 59 + 96 + 155 + 251 + 406 =
  16. 16.7 + 4 + 11 + 15 + 26 + 41 + 67 + 108 + 175 + 283 =
  17. 17.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  18. 18.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?
  19. 19.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?
  20. 20.A leapfrog list starts 1, 7 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): 7, 7, 14, 21, 35, 56, 91, 147, 238, 385. What is 11 × the 7th number?
  22. 22.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  23. 23.Leapfrog list (each number is the sum of the two before it): 4, 1, 5, 6, 11, 17, 28, 45, 73, 118. What is 11 × the 7th number?
  24. 24.A leapfrog list starts 5, 2 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): 7, 8, 15, 23, 38, 61, 99, 160, 259, 419. What is 11 × the 7th number?
  26. 26.3 + 2 + 5 + 7 + 12 + 19 + 31 + 50 + 81 + 131 =
  27. 27.5 + 3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 =
  28. 28.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?
  29. 29.A leapfrog list starts 5, 9 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  30. 30.Leapfrog list (each number is the sum of the two before it): 6, 9, 15, 24, 39, 63, 102, 165, 267, 432. What is 11 × the 7th number?
  31. 31.Leapfrog list (each number is the sum of the two before it): 2, 6, 8, 14, 22, 36, 58, 94, 152, 246. What is 11 × the 7th number?
  32. 32.9 + 7 + 16 + 23 + 39 + 62 + 101 + 163 + 264 + 427 =
  33. 33.8 + 8 + 16 + 24 + 40 + 64 + 104 + 168 + 272 + 440 =
  34. 34.2 + 7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 =
  35. 35.Leapfrog list (each number is the sum of the two before it): 5, 1, 6, 7, 13, 20, 33, 53, 86, 139. What is 11 × the 7th number?
  36. 36.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?
  37. 37.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?
  38. 38.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?
  39. 39.1 + 4 + 5 + 9 + 14 + 23 + 37 + 60 + 97 + 157 =
  40. 40.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =

Answer key

  1. 539
  2. 517
  3. 825
  4. 682
  5. 935
  6. 341
  7. 759
  8. 418
  9. 198
  10. 682
  11. 517
  12. 407
  13. 561
  14. 913
  15. 1056
  16. 737
  17. 594
  18. 759
  19. 1199
  20. 671
  21. 1001
  22. 1023
  23. 308
  24. 451
  25. 1089
  26. 341
  27. 539
  28. 704
  29. 1067
  30. 1122
  31. 638
  32. 1111
  33. 1144
  34. 726
  35. 363
  36. 374
  37. 253
  38. 770
  39. 407
  40. 583

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