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Leapfrog Sum Trick Worksheet

Maths tricks trick 25: The leapfrog sum trick · Set 345 · 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. 1.9 + 8 + 17 + 25 + 42 + 67 + 109 + 176 + 285 + 461 =
  2. 2.3 + 8 + 11 + 19 + 30 + 49 + 79 + 128 + 207 + 335 =
  3. 3.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?
  4. 4.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?
  5. 5.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?
  6. 6.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?
  7. 7.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?
  8. 8.9 + 1 + 10 + 11 + 21 + 32 + 53 + 85 + 138 + 223 =
  9. 9.1 + 6 + 7 + 13 + 20 + 33 + 53 + 86 + 139 + 225 =
  10. 10.9 + 6 + 15 + 21 + 36 + 57 + 93 + 150 + 243 + 393 =
  11. 11.A leapfrog list starts 7, 5 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 9, 3 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  13. 13.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?
  14. 14.Leapfrog list (each number is the sum of the two before it): 8, 8, 16, 24, 40, 64, 104, 168, 272, 440. What is 11 × the 7th number?
  15. 15.A leapfrog list starts 4, 1 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  16. 16.4 + 3 + 7 + 10 + 17 + 27 + 44 + 71 + 115 + 186 =
  17. 17.A leapfrog list starts 1, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  18. 18.Leapfrog list (each number is the sum of the two before it): 6, 2, 8, 10, 18, 28, 46, 74, 120, 194. What is 11 × the 7th number?
  19. 19.A leapfrog list starts 7, 6 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  20. 20.2 + 9 + 11 + 20 + 31 + 51 + 82 + 133 + 215 + 348 =
  21. 21.A leapfrog list starts 6, 2 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  22. 22.7 + 9 + 16 + 25 + 41 + 66 + 107 + 173 + 280 + 453 =
  23. 23.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?
  24. 24.A leapfrog list starts 5, 8 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  25. 25.6 + 2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 =
  26. 26.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?
  27. 27.3 + 3 + 6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 =
  28. 28.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?
  29. 29.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?
  30. 30.Leapfrog list (each number is the sum of the two before it): 7, 9, 16, 25, 41, 66, 107, 173, 280, 453. What is 11 × the 7th number?
  31. 31.6 + 9 + 15 + 24 + 39 + 63 + 102 + 165 + 267 + 432 =
  32. 32.A leapfrog list starts 9, 5 and each next number is the sum of the two before it. What do the first 10 numbers add up to?
  33. 33.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?
  34. 34.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?
  35. 35.3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 + 369 =
  36. 36.Leapfrog list (each number is the sum of the two before it): 3, 6, 9, 15, 24, 39, 63, 102, 165, 267. What is 11 × the 7th number?
  37. 37.6 + 3 + 9 + 12 + 21 + 33 + 54 + 87 + 141 + 228 =
  38. 38.2 + 8 + 10 + 18 + 28 + 46 + 74 + 120 + 194 + 314 =
  39. 39.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?
  40. 40.1 + 8 + 9 + 17 + 26 + 43 + 69 + 112 + 181 + 293 =

Answer key

  1. 1199
  2. 869
  3. 231
  4. 396
  5. 583
  6. 143
  7. 1287
  8. 583
  9. 583
  10. 1023
  11. 825
  12. 759
  13. 374
  14. 1144
  15. 308
  16. 484
  17. 495
  18. 506
  19. 913
  20. 902
  21. 506
  22. 1177
  23. 968
  24. 979
  25. 506
  26. 341
  27. 429
  28. 638
  29. 759
  30. 1177
  31. 1122
  32. 935
  33. 726
  34. 198
  35. 957
  36. 693
  37. 594
  38. 814
  39. 1199
  40. 759

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